[python] readonly constructors (#9409)

* readonly

* other tests

* doc

* python samples

* model utils

samples/openapi3/client/petstore/python/.openapi-generator/FILES

@@ -64,6 +64,7 @@ docs/MapTest.md
 docs/MixedPropertiesAndAdditionalPropertiesClass.md
 docs/Model200Response.md
 docs/ModelReturn.md
+docs/Mole.md
 docs/Name.md
 docs/NullableClass.md
 docs/NullableShape.md
@@ -173,6 +174,7 @@ petstore_api/model/map_test.py
 petstore_api/model/mixed_properties_and_additional_properties_class.py
 petstore_api/model/model200_response.py
 petstore_api/model/model_return.py
+petstore_api/model/mole.py
 petstore_api/model/name.py
 petstore_api/model/nullable_class.py
 petstore_api/model/nullable_shape.py

samples/openapi3/client/petstore/python/README.md

@@ -192,6 +192,7 @@ Class | Method | HTTP request | Description
  - [MixedPropertiesAndAdditionalPropertiesClass](docs/MixedPropertiesAndAdditionalPropertiesClass.md)
  - [Model200Response](docs/Model200Response.md)
  - [ModelReturn](docs/ModelReturn.md)
+ - [Mole](docs/Mole.md)
  - [Name](docs/Name.md)
  - [NullableClass](docs/NullableClass.md)
  - [NullableShape](docs/NullableShape.md)

samples/openapi3/client/petstore/python/docs/Mole.md

@@ -0,0 +1,17 @@
+# Mole
+
+
+## Properties
+Name | Type | Description | Notes
+------------ | ------------- | ------------- | -------------
+**blind** | **bool** |  | [readonly] 
+**smell** | **str** |  | 
+**hearing** | **bool** |  | 
+**touch** | **bool** |  | [optional] [readonly] 
+**taste** | **str** |  | [optional] 
+**seeing_ghosts** | **bool** |  | [optional] 
+**any string name** | **bool, date, datetime, dict, float, int, list, str, none_type** | any string name can be used but the value must be the correct type | [optional]
+
+[[Back to Model list]](../README.md#documentation-for-models) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to README]](../README.md)
+
+

samples/openapi3/client/petstore/python/petstore_api/model/additional_properties_class.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class AdditionalPropertiesClass(ModelNormal):
@@ -104,8 +107,92 @@ class AdditionalPropertiesClass(ModelNormal):
         'map_with_undeclared_properties_string': 'map_with_undeclared_properties_string',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """AdditionalPropertiesClass - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            map_property ({str: (str,)}): [optional]  # noqa: E501
+            map_of_map_property ({str: ({str: (str,)},)}): [optional]  # noqa: E501
+            anytype_1 (bool, date, datetime, dict, float, int, list, str, none_type): [optional]  # noqa: E501
+            map_with_undeclared_properties_anytype_1 ({str: (bool, date, datetime, dict, float, int, list, str, none_type)}): [optional]  # noqa: E501
+            map_with_undeclared_properties_anytype_2 ({str: (bool, date, datetime, dict, float, int, list, str, none_type)}): [optional]  # noqa: E501
+            map_with_undeclared_properties_anytype_3 ({str: (bool, date, datetime, dict, float, int, list, str, none_type)}): [optional]  # noqa: E501
+            empty_map (dict): an object with no declared properties and no undeclared properties, hence it's an empty map.. [optional]  # noqa: E501
+            map_with_undeclared_properties_string ({str: (str,)}): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -191,3 +278,6 @@ class AdditionalPropertiesClass(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/additional_properties_with_array_of_enums.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.enum_class import EnumClass
@@ -94,8 +97,84 @@ class AdditionalPropertiesWithArrayOfEnums(ModelNormal):
     attribute_map = {
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """AdditionalPropertiesWithArrayOfEnums - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -173,3 +252,6 @@ class AdditionalPropertiesWithArrayOfEnums(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/address.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class Address(ModelNormal):
@@ -88,8 +91,84 @@ class Address(ModelNormal):
     attribute_map = {
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """Address - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -167,3 +246,6 @@ class Address(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/animal.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.cat import Cat
@@ -106,8 +109,89 @@ class Animal(ModelNormal):
         'color': 'color',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, class_name, *args, **kwargs):  # noqa: E501
+        """Animal - a model defined in OpenAPI
+
+        Args:
+            class_name (str):
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            color (str): [optional] if omitted the server will use the default value of "red"  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        self.class_name = class_name
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -190,3 +274,6 @@ class Animal(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/animal_farm.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.animal import Animal
@@ -90,6 +93,8 @@ class AnimalFarm(ModelSimple):
 
     attribute_map = {}
 
+    read_only_vars = set()
+
     _composed_schemas = None
 
     required_properties = set([
@@ -189,3 +194,97 @@ class AnimalFarm(ModelSimple):
                 path_to_item=_path_to_item,
                 valid_classes=(self.__class__,),
             )
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):
+        """AnimalFarm - a model defined in OpenAPI
+
+        Note that value can be passed either in args or in kwargs, but not in both.
+
+        Args:
+            args[0] ([Animal]):  # noqa: E501
+
+        Keyword Args:
+            value ([Animal]):  # noqa: E501
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+        # required up here when default value is not given
+        _path_to_item = kwargs.pop('_path_to_item', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if 'value' in kwargs:
+            value = kwargs.pop('value')
+        elif args:
+            args = list(args)
+            value = args.pop(0)
+        else:
+            raise ApiTypeError(
+                "value is required, but not passed in args or kwargs and doesn't have default",
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+        self.value = value
+        if kwargs:
+            raise ApiTypeError(
+                "Invalid named arguments=%s passed to %s. Remove those invalid named arguments." % (
+                    kwargs,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        return self

samples/openapi3/client/petstore/python/petstore_api/model/api_response.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class ApiResponse(ModelNormal):
@@ -94,8 +97,87 @@ class ApiResponse(ModelNormal):
         'message': 'message',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """ApiResponse - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            code (int): [optional]  # noqa: E501
+            type (str): [optional]  # noqa: E501
+            message (str): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -176,3 +258,6 @@ class ApiResponse(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/apple.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class Apple(ModelNormal):
@@ -103,8 +106,89 @@ class Apple(ModelNormal):
         'origin': 'origin',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, cultivar, *args, **kwargs):  # noqa: E501
+        """Apple - a model defined in OpenAPI
+
+        Args:
+            cultivar (str):
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            origin (str): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        self.cultivar = cultivar
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -187,3 +271,6 @@ class Apple(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/apple_req.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class AppleReq(ModelNormal):
@@ -86,8 +89,89 @@ class AppleReq(ModelNormal):
         'mealy': 'mealy',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, cultivar, *args, **kwargs):  # noqa: E501
+        """AppleReq - a model defined in OpenAPI
+
+        Args:
+            cultivar (str):
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            mealy (bool): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        self.cultivar = cultivar
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -170,3 +254,6 @@ class AppleReq(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/array_of_array_of_number_only.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class ArrayOfArrayOfNumberOnly(ModelNormal):
@@ -90,8 +93,85 @@ class ArrayOfArrayOfNumberOnly(ModelNormal):
         'array_array_number': 'ArrayArrayNumber',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """ArrayOfArrayOfNumberOnly - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            array_array_number ([[float]]): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -170,3 +250,6 @@ class ArrayOfArrayOfNumberOnly(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/array_of_enums.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.string_enum import StringEnum
@@ -90,6 +93,8 @@ class ArrayOfEnums(ModelSimple):
 
     attribute_map = {}
 
+    read_only_vars = set()
+
     _composed_schemas = None
 
     required_properties = set([
@@ -189,3 +194,97 @@ class ArrayOfEnums(ModelSimple):
                 path_to_item=_path_to_item,
                 valid_classes=(self.__class__,),
             )
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):
+        """ArrayOfEnums - a model defined in OpenAPI
+
+        Note that value can be passed either in args or in kwargs, but not in both.
+
+        Args:
+            args[0] ([StringEnum]):  # noqa: E501
+
+        Keyword Args:
+            value ([StringEnum]):  # noqa: E501
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+        # required up here when default value is not given
+        _path_to_item = kwargs.pop('_path_to_item', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if 'value' in kwargs:
+            value = kwargs.pop('value')
+        elif args:
+            args = list(args)
+            value = args.pop(0)
+        else:
+            raise ApiTypeError(
+                "value is required, but not passed in args or kwargs and doesn't have default",
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+        self.value = value
+        if kwargs:
+            raise ApiTypeError(
+                "Invalid named arguments=%s passed to %s. Remove those invalid named arguments." % (
+                    kwargs,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        return self

samples/openapi3/client/petstore/python/petstore_api/model/array_of_number_only.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class ArrayOfNumberOnly(ModelNormal):
@@ -90,8 +93,85 @@ class ArrayOfNumberOnly(ModelNormal):
         'array_number': 'ArrayNumber',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """ArrayOfNumberOnly - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            array_number ([float]): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -170,3 +250,6 @@ class ArrayOfNumberOnly(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/array_test.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.read_only_first import ReadOnlyFirst
@@ -100,8 +103,87 @@ class ArrayTest(ModelNormal):
         'array_array_of_model': 'array_array_of_model',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """ArrayTest - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            array_of_string ([str]): [optional]  # noqa: E501
+            array_array_of_integer ([[int]]): [optional]  # noqa: E501
+            array_array_of_model ([[ReadOnlyFirst]]): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -182,3 +264,6 @@ class ArrayTest(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/banana.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class Banana(ModelNormal):
@@ -90,8 +93,88 @@ class Banana(ModelNormal):
         'length_cm': 'lengthCm',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, length_cm, *args, **kwargs):  # noqa: E501
+        """Banana - a model defined in OpenAPI
+
+        Args:
+            length_cm (float):
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        self.length_cm = length_cm
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -173,3 +256,6 @@ class Banana(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/banana_req.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class BananaReq(ModelNormal):
@@ -86,8 +89,89 @@ class BananaReq(ModelNormal):
         'sweet': 'sweet',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, length_cm, *args, **kwargs):  # noqa: E501
+        """BananaReq - a model defined in OpenAPI
+
+        Args:
+            length_cm (float):
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            sweet (bool): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        self.length_cm = length_cm
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -170,3 +254,6 @@ class BananaReq(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/basque_pig.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class BasquePig(ModelNormal):
@@ -90,8 +93,88 @@ class BasquePig(ModelNormal):
         'class_name': 'className',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, class_name, *args, **kwargs):  # noqa: E501
+        """BasquePig - a model defined in OpenAPI
+
+        Args:
+            class_name (str):
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        self.class_name = class_name
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -173,3 +256,6 @@ class BasquePig(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/capitalization.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class Capitalization(ModelNormal):
@@ -100,8 +103,90 @@ class Capitalization(ModelNormal):
         'att_name': 'ATT_NAME',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """Capitalization - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            small_camel (str): [optional]  # noqa: E501
+            capital_camel (str): [optional]  # noqa: E501
+            small_snake (str): [optional]  # noqa: E501
+            capital_snake (str): [optional]  # noqa: E501
+            sca_eth_flow_points (str): [optional]  # noqa: E501
+            att_name (str): Name of the pet . [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -185,3 +270,6 @@ class Capitalization(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/cat.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.animal import Animal
@@ -105,6 +108,100 @@ class Cat(ModelComposed):
         'color': 'color',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """Cat - a model defined in OpenAPI
+
+        Keyword Args:
+            class_name (str):
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            declawed (bool): [optional]  # noqa: E501
+            color (str): [optional] if omitted the server will use the default value of "red"  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        constant_args = {
+            '_check_type': _check_type,
+            '_path_to_item': _path_to_item,
+            '_spec_property_naming': _spec_property_naming,
+            '_configuration': _configuration,
+            '_visited_composed_classes': self._visited_composed_classes,
+        }
+        composed_info = validate_get_composed_info(
+            constant_args, kwargs, self)
+        self._composed_instances = composed_info[0]
+        self._var_name_to_model_instances = composed_info[1]
+        self._additional_properties_model_instances = composed_info[2]
+        discarded_args = composed_info[3]
+
+        for var_name, var_value in kwargs.items():
+            if var_name in discarded_args and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self._additional_properties_model_instances:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -202,6 +299,9 @@ class Cat(ModelComposed):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")
 
     @cached_property
     def _composed_schemas():

samples/openapi3/client/petstore/python/petstore_api/model/cat_all_of.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class CatAllOf(ModelNormal):
@@ -90,8 +93,85 @@ class CatAllOf(ModelNormal):
         'declawed': 'declawed',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """CatAllOf - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            declawed (bool): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -170,3 +250,6 @@ class CatAllOf(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/category.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class Category(ModelNormal):
@@ -92,8 +95,90 @@ class Category(ModelNormal):
         'id': 'id',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """Category - a model defined in OpenAPI
+
+        Args:
+
+        Keyword Args:
+            name (str): defaults to "default-name"  # noqa: E501
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            id (int): [optional]  # noqa: E501
+        """
+
+        name = kwargs.get('name', "default-name")
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        self.name = name
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -177,3 +262,6 @@ class Category(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/child_cat.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.child_cat_all_of import ChildCatAllOf
@@ -103,6 +106,99 @@ class ChildCat(ModelComposed):
         'name': 'name',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """ChildCat - a model defined in OpenAPI
+
+        Keyword Args:
+            pet_type (str):
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            name (str): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        constant_args = {
+            '_check_type': _check_type,
+            '_path_to_item': _path_to_item,
+            '_spec_property_naming': _spec_property_naming,
+            '_configuration': _configuration,
+            '_visited_composed_classes': self._visited_composed_classes,
+        }
+        composed_info = validate_get_composed_info(
+            constant_args, kwargs, self)
+        self._composed_instances = composed_info[0]
+        self._var_name_to_model_instances = composed_info[1]
+        self._additional_properties_model_instances = composed_info[2]
+        discarded_args = composed_info[3]
+
+        for var_name, var_value in kwargs.items():
+            if var_name in discarded_args and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self._additional_properties_model_instances:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -199,6 +295,9 @@ class ChildCat(ModelComposed):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")
 
     @cached_property
     def _composed_schemas():

samples/openapi3/client/petstore/python/petstore_api/model/child_cat_all_of.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class ChildCatAllOf(ModelNormal):
@@ -90,8 +93,85 @@ class ChildCatAllOf(ModelNormal):
         'name': 'name',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """ChildCatAllOf - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            name (str): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -170,3 +250,6 @@ class ChildCatAllOf(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/class_model.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class ClassModel(ModelNormal):
@@ -90,8 +93,85 @@ class ClassModel(ModelNormal):
         '_class': '_class',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """ClassModel - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            _class (str): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -170,3 +250,6 @@ class ClassModel(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/client.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class Client(ModelNormal):
@@ -90,8 +93,85 @@ class Client(ModelNormal):
         'client': 'client',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """Client - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            client (str): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -170,3 +250,6 @@ class Client(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/complex_quadrilateral.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.quadrilateral_interface import QuadrilateralInterface
@@ -100,6 +103,99 @@ class ComplexQuadrilateral(ModelComposed):
         'quadrilateral_type': 'quadrilateralType',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """ComplexQuadrilateral - a model defined in OpenAPI
+
+        Keyword Args:
+            shape_type (str):
+            quadrilateral_type (str):
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        constant_args = {
+            '_check_type': _check_type,
+            '_path_to_item': _path_to_item,
+            '_spec_property_naming': _spec_property_naming,
+            '_configuration': _configuration,
+            '_visited_composed_classes': self._visited_composed_classes,
+        }
+        composed_info = validate_get_composed_info(
+            constant_args, kwargs, self)
+        self._composed_instances = composed_info[0]
+        self._var_name_to_model_instances = composed_info[1]
+        self._additional_properties_model_instances = composed_info[2]
+        discarded_args = composed_info[3]
+
+        for var_name, var_value in kwargs.items():
+            if var_name in discarded_args and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self._additional_properties_model_instances:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -196,6 +292,9 @@ class ComplexQuadrilateral(ModelComposed):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")
 
     @cached_property
     def _composed_schemas():

samples/openapi3/client/petstore/python/petstore_api/model/composed_one_of_number_with_validations.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.animal import Animal
@@ -100,6 +103,99 @@ class ComposedOneOfNumberWithValidations(ModelComposed):
         'class_name': 'className',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """ComposedOneOfNumberWithValidations - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            color (str): [optional] if omitted the server will use the default value of "red"  # noqa: E501
+            class_name (str): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        constant_args = {
+            '_check_type': _check_type,
+            '_path_to_item': _path_to_item,
+            '_spec_property_naming': _spec_property_naming,
+            '_configuration': _configuration,
+            '_visited_composed_classes': self._visited_composed_classes,
+        }
+        composed_info = validate_get_composed_info(
+            constant_args, kwargs, self)
+        self._composed_instances = composed_info[0]
+        self._var_name_to_model_instances = composed_info[1]
+        self._additional_properties_model_instances = composed_info[2]
+        discarded_args = composed_info[3]
+
+        for var_name, var_value in kwargs.items():
+            if var_name in discarded_args and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self._additional_properties_model_instances:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -196,6 +292,9 @@ class ComposedOneOfNumberWithValidations(ModelComposed):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")
 
     @cached_property
     def _composed_schemas():

samples/openapi3/client/petstore/python/petstore_api/model/composed_schema_with_props_and_no_add_props.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.tag import Tag
@@ -93,6 +96,100 @@ class ComposedSchemaWithPropsAndNoAddProps(ModelComposed):
         'name': 'name',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """ComposedSchemaWithPropsAndNoAddProps - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            color (str): [optional]  # noqa: E501
+            id (int): [optional]  # noqa: E501
+            name (str): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        constant_args = {
+            '_check_type': _check_type,
+            '_path_to_item': _path_to_item,
+            '_spec_property_naming': _spec_property_naming,
+            '_configuration': _configuration,
+            '_visited_composed_classes': self._visited_composed_classes,
+        }
+        composed_info = validate_get_composed_info(
+            constant_args, kwargs, self)
+        self._composed_instances = composed_info[0]
+        self._var_name_to_model_instances = composed_info[1]
+        self._additional_properties_model_instances = composed_info[2]
+        discarded_args = composed_info[3]
+
+        for var_name, var_value in kwargs.items():
+            if var_name in discarded_args and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self._additional_properties_model_instances:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -190,6 +287,9 @@ class ComposedSchemaWithPropsAndNoAddProps(ModelComposed):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")
 
     @cached_property
     def _composed_schemas():

samples/openapi3/client/petstore/python/petstore_api/model/danish_pig.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class DanishPig(ModelNormal):
@@ -90,8 +93,88 @@ class DanishPig(ModelNormal):
         'class_name': 'className',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, class_name, *args, **kwargs):  # noqa: E501
+        """DanishPig - a model defined in OpenAPI
+
+        Args:
+            class_name (str):
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        self.class_name = class_name
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -173,3 +256,6 @@ class DanishPig(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/dog.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.animal import Animal
@@ -105,6 +108,100 @@ class Dog(ModelComposed):
         'color': 'color',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """Dog - a model defined in OpenAPI
+
+        Keyword Args:
+            class_name (str):
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            breed (str): [optional]  # noqa: E501
+            color (str): [optional] if omitted the server will use the default value of "red"  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        constant_args = {
+            '_check_type': _check_type,
+            '_path_to_item': _path_to_item,
+            '_spec_property_naming': _spec_property_naming,
+            '_configuration': _configuration,
+            '_visited_composed_classes': self._visited_composed_classes,
+        }
+        composed_info = validate_get_composed_info(
+            constant_args, kwargs, self)
+        self._composed_instances = composed_info[0]
+        self._var_name_to_model_instances = composed_info[1]
+        self._additional_properties_model_instances = composed_info[2]
+        discarded_args = composed_info[3]
+
+        for var_name, var_value in kwargs.items():
+            if var_name in discarded_args and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self._additional_properties_model_instances:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -202,6 +299,9 @@ class Dog(ModelComposed):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")
 
     @cached_property
     def _composed_schemas():

samples/openapi3/client/petstore/python/petstore_api/model/dog_all_of.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class DogAllOf(ModelNormal):
@@ -90,8 +93,85 @@ class DogAllOf(ModelNormal):
         'breed': 'breed',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """DogAllOf - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            breed (str): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -170,3 +250,6 @@ class DogAllOf(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/drawing.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.fruit import Fruit
@@ -108,8 +111,88 @@ class Drawing(ModelNormal):
         'shapes': 'shapes',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """Drawing - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            main_shape (Shape): [optional]  # noqa: E501
+            shape_or_null (ShapeOrNull): [optional]  # noqa: E501
+            nullable_shape (NullableShape): [optional]  # noqa: E501
+            shapes ([Shape]): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -191,3 +274,6 @@ class Drawing(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/enum_arrays.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class EnumArrays(ModelNormal):
@@ -100,8 +103,86 @@ class EnumArrays(ModelNormal):
         'array_enum': 'array_enum',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """EnumArrays - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            just_symbol (str): [optional]  # noqa: E501
+            array_enum ([str]): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -181,3 +262,6 @@ class EnumArrays(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/enum_class.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class EnumClass(ModelSimple):
@@ -89,6 +92,8 @@ class EnumClass(ModelSimple):
 
     attribute_map = {}
 
+    read_only_vars = set()
+
     _composed_schemas = None
 
     required_properties = set([
@@ -184,3 +189,93 @@ class EnumClass(ModelSimple):
                 path_to_item=_path_to_item,
                 valid_classes=(self.__class__,),
             )
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):
+        """EnumClass - a model defined in OpenAPI
+
+        Note that value can be passed either in args or in kwargs, but not in both.
+
+        Args:
+            args[0] (str): if omitted defaults to "-efg", must be one of ["_abc", "-efg", "(xyz)", ]  # noqa: E501
+
+        Keyword Args:
+            value (str): if omitted defaults to "-efg", must be one of ["_abc", "-efg", "(xyz)", ]  # noqa: E501
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+        # required up here when default value is not given
+        _path_to_item = kwargs.pop('_path_to_item', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if 'value' in kwargs:
+            value = kwargs.pop('value')
+        elif args:
+            args = list(args)
+            value = args.pop(0)
+        else:
+            value = "-efg"
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+        self.value = value
+        if kwargs:
+            raise ApiTypeError(
+                "Invalid named arguments=%s passed to %s. Remove those invalid named arguments." % (
+                    kwargs,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        return self

samples/openapi3/client/petstore/python/petstore_api/model/enum_test.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.array_of_enums import ArrayOfEnums
@@ -144,8 +147,98 @@ class EnumTest(ModelNormal):
         'array_of_str_enum': 'ArrayOfStrEnum',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, enum_string_required, *args, **kwargs):  # noqa: E501
+        """EnumTest - a model defined in OpenAPI
+
+        Args:
+            enum_string_required (str):
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            enum_string (str): [optional]  # noqa: E501
+            enum_integer (int): [optional]  # noqa: E501
+            enum_number (float): [optional]  # noqa: E501
+            string_enum (StringEnum): [optional]  # noqa: E501
+            integer_enum (IntegerEnum): [optional]  # noqa: E501
+            string_enum_with_default_value (StringEnumWithDefaultValue): [optional]  # noqa: E501
+            integer_enum_with_default_value (IntegerEnumWithDefaultValue): [optional]  # noqa: E501
+            integer_enum_one_value (IntegerEnumOneValue): [optional]  # noqa: E501
+            inline_array_of_str_enum ([StringEnum]): [optional]  # noqa: E501
+            array_of_str_enum (ArrayOfEnums): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        self.enum_string_required = enum_string_required
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -237,3 +330,6 @@ class EnumTest(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/equilateral_triangle.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.shape_interface import ShapeInterface
@@ -100,6 +103,99 @@ class EquilateralTriangle(ModelComposed):
         'triangle_type': 'triangleType',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """EquilateralTriangle - a model defined in OpenAPI
+
+        Keyword Args:
+            shape_type (str):
+            triangle_type (str):
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        constant_args = {
+            '_check_type': _check_type,
+            '_path_to_item': _path_to_item,
+            '_spec_property_naming': _spec_property_naming,
+            '_configuration': _configuration,
+            '_visited_composed_classes': self._visited_composed_classes,
+        }
+        composed_info = validate_get_composed_info(
+            constant_args, kwargs, self)
+        self._composed_instances = composed_info[0]
+        self._var_name_to_model_instances = composed_info[1]
+        self._additional_properties_model_instances = composed_info[2]
+        discarded_args = composed_info[3]
+
+        for var_name, var_value in kwargs.items():
+            if var_name in discarded_args and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self._additional_properties_model_instances:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -196,6 +292,9 @@ class EquilateralTriangle(ModelComposed):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")
 
     @cached_property
     def _composed_schemas():

samples/openapi3/client/petstore/python/petstore_api/model/fake_get_inline_additional_properties_payload_array_data.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class FakeGetInlineAdditionalPropertiesPayloadArrayData(ModelNormal):
@@ -90,8 +93,85 @@ class FakeGetInlineAdditionalPropertiesPayloadArrayData(ModelNormal):
         'labels': 'labels',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """FakeGetInlineAdditionalPropertiesPayloadArrayData - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            labels ([str, none_type]): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -170,3 +250,6 @@ class FakeGetInlineAdditionalPropertiesPayloadArrayData(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/file.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class File(ModelNormal):
@@ -90,8 +93,85 @@ class File(ModelNormal):
         'source_uri': 'sourceURI',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """File - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            source_uri (str): Test capitalization. [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -170,3 +250,6 @@ class File(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/file_schema_test_class.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.file import File
@@ -98,8 +101,86 @@ class FileSchemaTestClass(ModelNormal):
         'files': 'files',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """FileSchemaTestClass - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            file (File): [optional]  # noqa: E501
+            files ([File]): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -179,3 +260,6 @@ class FileSchemaTestClass(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/foo.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class Foo(ModelNormal):
@@ -90,8 +93,85 @@ class Foo(ModelNormal):
         'bar': 'bar',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """Foo - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            bar (str): [optional] if omitted the server will use the default value of "bar"  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -170,3 +250,6 @@ class Foo(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/format_test.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class FormatTest(ModelNormal):
@@ -163,8 +166,106 @@ class FormatTest(ModelNormal):
         'pattern_with_digits_and_delimiter': 'pattern_with_digits_and_delimiter',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, number, byte, date, password, *args, **kwargs):  # noqa: E501
+        """FormatTest - a model defined in OpenAPI
+
+        Args:
+            number (float):
+            byte (str):
+            date (date):
+            password (str):
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            integer (int): [optional]  # noqa: E501
+            int32 (int): [optional]  # noqa: E501
+            int64 (int): [optional]  # noqa: E501
+            float (float): [optional]  # noqa: E501
+            double (float): [optional]  # noqa: E501
+            string (str): [optional]  # noqa: E501
+            binary (file_type): [optional]  # noqa: E501
+            date_time (datetime): [optional]  # noqa: E501
+            uuid (str): [optional]  # noqa: E501
+            uuid_no_example (str): [optional]  # noqa: E501
+            pattern_with_digits (str): A string that is a 10 digit number. Can have leading zeros.. [optional]  # noqa: E501
+            pattern_with_digits_and_delimiter (str): A string starting with 'image_' (case insensitive) and one to three digits following i.e. Image_01.. [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        self.number = number
+        self.byte = byte
+        self.date = date
+        self.password = password
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -264,3 +365,6 @@ class FormatTest(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/fruit.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.apple import Apple
@@ -115,6 +118,101 @@ class Fruit(ModelComposed):
         'origin': 'origin',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """Fruit - a model defined in OpenAPI
+
+        Keyword Args:
+            cultivar (str):
+            length_cm (float):
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            color (str): [optional]  # noqa: E501
+            origin (str): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        constant_args = {
+            '_check_type': _check_type,
+            '_path_to_item': _path_to_item,
+            '_spec_property_naming': _spec_property_naming,
+            '_configuration': _configuration,
+            '_visited_composed_classes': self._visited_composed_classes,
+        }
+        composed_info = validate_get_composed_info(
+            constant_args, kwargs, self)
+        self._composed_instances = composed_info[0]
+        self._var_name_to_model_instances = composed_info[1]
+        self._additional_properties_model_instances = composed_info[2]
+        discarded_args = composed_info[3]
+
+        for var_name, var_value in kwargs.items():
+            if var_name in discarded_args and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self._additional_properties_model_instances:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -213,6 +311,9 @@ class Fruit(ModelComposed):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")
 
     @cached_property
     def _composed_schemas():

samples/openapi3/client/petstore/python/petstore_api/model/fruit_req.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.apple_req import AppleReq
@@ -104,6 +107,101 @@ class FruitReq(ModelComposed):
         'length_cm': 'lengthCm',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """FruitReq - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            mealy (bool): [optional]  # noqa: E501
+            sweet (bool): [optional]  # noqa: E501
+            cultivar (str): [optional]  # noqa: E501
+            length_cm (float): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        constant_args = {
+            '_check_type': _check_type,
+            '_path_to_item': _path_to_item,
+            '_spec_property_naming': _spec_property_naming,
+            '_configuration': _configuration,
+            '_visited_composed_classes': self._visited_composed_classes,
+        }
+        composed_info = validate_get_composed_info(
+            constant_args, kwargs, self)
+        self._composed_instances = composed_info[0]
+        self._var_name_to_model_instances = composed_info[1]
+        self._additional_properties_model_instances = composed_info[2]
+        discarded_args = composed_info[3]
+
+        for var_name, var_value in kwargs.items():
+            if var_name in discarded_args and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self._additional_properties_model_instances:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -202,6 +300,9 @@ class FruitReq(ModelComposed):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")
 
     @cached_property
     def _composed_schemas():

samples/openapi3/client/petstore/python/petstore_api/model/gm_fruit.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.apple import Apple
@@ -115,6 +118,101 @@ class GmFruit(ModelComposed):
         'origin': 'origin',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """GmFruit - a model defined in OpenAPI
+
+        Keyword Args:
+            cultivar (str):
+            length_cm (float):
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            color (str): [optional]  # noqa: E501
+            origin (str): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        constant_args = {
+            '_check_type': _check_type,
+            '_path_to_item': _path_to_item,
+            '_spec_property_naming': _spec_property_naming,
+            '_configuration': _configuration,
+            '_visited_composed_classes': self._visited_composed_classes,
+        }
+        composed_info = validate_get_composed_info(
+            constant_args, kwargs, self)
+        self._composed_instances = composed_info[0]
+        self._var_name_to_model_instances = composed_info[1]
+        self._additional_properties_model_instances = composed_info[2]
+        discarded_args = composed_info[3]
+
+        for var_name, var_value in kwargs.items():
+            if var_name in discarded_args and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self._additional_properties_model_instances:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -213,6 +311,9 @@ class GmFruit(ModelComposed):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")
 
     @cached_property
     def _composed_schemas():

samples/openapi3/client/petstore/python/petstore_api/model/grandparent_animal.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.child_cat import ChildCat
@@ -104,8 +107,88 @@ class GrandparentAnimal(ModelNormal):
         'pet_type': 'pet_type',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, pet_type, *args, **kwargs):  # noqa: E501
+        """GrandparentAnimal - a model defined in OpenAPI
+
+        Args:
+            pet_type (str):
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        self.pet_type = pet_type
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -187,3 +270,6 @@ class GrandparentAnimal(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/has_only_read_only.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class HasOnlyReadOnly(ModelNormal):
@@ -92,8 +95,88 @@ class HasOnlyReadOnly(ModelNormal):
         'foo': 'foo',  # noqa: E501
     }
 
+    read_only_vars = {
+        'bar',  # noqa: E501
+        'foo',  # noqa: E501
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """HasOnlyReadOnly - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            bar (str): [optional]  # noqa: E501
+            foo (str): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -173,3 +256,6 @@ class HasOnlyReadOnly(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/health_check_result.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class HealthCheckResult(ModelNormal):
@@ -90,8 +93,85 @@ class HealthCheckResult(ModelNormal):
         'nullable_message': 'NullableMessage',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """HealthCheckResult - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            nullable_message (str, none_type): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -170,3 +250,6 @@ class HealthCheckResult(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/inline_additional_properties_ref_payload.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.fake_get_inline_additional_properties_payload_array_data import FakeGetInlineAdditionalPropertiesPayloadArrayData
@@ -96,8 +99,85 @@ class InlineAdditionalPropertiesRefPayload(ModelNormal):
         'array_data': 'arrayData',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """InlineAdditionalPropertiesRefPayload - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            array_data ([FakeGetInlineAdditionalPropertiesPayloadArrayData], none_type): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -176,3 +256,6 @@ class InlineAdditionalPropertiesRefPayload(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/inline_object6.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.fake_get_inline_additional_properties_payload_array_data import FakeGetInlineAdditionalPropertiesPayloadArrayData
@@ -96,8 +99,85 @@ class InlineObject6(ModelNormal):
         'array_data': 'arrayData',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """InlineObject6 - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            array_data ([FakeGetInlineAdditionalPropertiesPayloadArrayData], none_type): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -176,3 +256,6 @@ class InlineObject6(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/inline_response_default.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.foo import Foo
@@ -96,8 +99,85 @@ class InlineResponseDefault(ModelNormal):
         'string': 'string',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """InlineResponseDefault - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            string (Foo): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -176,3 +256,6 @@ class InlineResponseDefault(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/integer_enum.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class IntegerEnum(ModelSimple):
@@ -89,6 +92,8 @@ class IntegerEnum(ModelSimple):
 
     attribute_map = {}
 
+    read_only_vars = set()
+
     _composed_schemas = None
 
     required_properties = set([
@@ -188,3 +193,97 @@ class IntegerEnum(ModelSimple):
                 path_to_item=_path_to_item,
                 valid_classes=(self.__class__,),
             )
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):
+        """IntegerEnum - a model defined in OpenAPI
+
+        Note that value can be passed either in args or in kwargs, but not in both.
+
+        Args:
+            args[0] (int):, must be one of [0, 1, 2, ]  # noqa: E501
+
+        Keyword Args:
+            value (int):, must be one of [0, 1, 2, ]  # noqa: E501
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+        # required up here when default value is not given
+        _path_to_item = kwargs.pop('_path_to_item', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if 'value' in kwargs:
+            value = kwargs.pop('value')
+        elif args:
+            args = list(args)
+            value = args.pop(0)
+        else:
+            raise ApiTypeError(
+                "value is required, but not passed in args or kwargs and doesn't have default",
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+        self.value = value
+        if kwargs:
+            raise ApiTypeError(
+                "Invalid named arguments=%s passed to %s. Remove those invalid named arguments." % (
+                    kwargs,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        return self

samples/openapi3/client/petstore/python/petstore_api/model/integer_enum_one_value.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class IntegerEnumOneValue(ModelSimple):
@@ -87,6 +90,8 @@ class IntegerEnumOneValue(ModelSimple):
 
     attribute_map = {}
 
+    read_only_vars = set()
+
     _composed_schemas = None
 
     required_properties = set([
@@ -182,3 +187,93 @@ class IntegerEnumOneValue(ModelSimple):
                 path_to_item=_path_to_item,
                 valid_classes=(self.__class__,),
             )
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):
+        """IntegerEnumOneValue - a model defined in OpenAPI
+
+        Note that value can be passed either in args or in kwargs, but not in both.
+
+        Args:
+            args[0] (int): if omitted defaults to 0, must be one of [0, ]  # noqa: E501
+
+        Keyword Args:
+            value (int): if omitted defaults to 0, must be one of [0, ]  # noqa: E501
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+        # required up here when default value is not given
+        _path_to_item = kwargs.pop('_path_to_item', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if 'value' in kwargs:
+            value = kwargs.pop('value')
+        elif args:
+            args = list(args)
+            value = args.pop(0)
+        else:
+            value = 0
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+        self.value = value
+        if kwargs:
+            raise ApiTypeError(
+                "Invalid named arguments=%s passed to %s. Remove those invalid named arguments." % (
+                    kwargs,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        return self

samples/openapi3/client/petstore/python/petstore_api/model/integer_enum_with_default_value.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class IntegerEnumWithDefaultValue(ModelSimple):
@@ -89,6 +92,8 @@ class IntegerEnumWithDefaultValue(ModelSimple):
 
     attribute_map = {}
 
+    read_only_vars = set()
+
     _composed_schemas = None
 
     required_properties = set([
@@ -184,3 +189,93 @@ class IntegerEnumWithDefaultValue(ModelSimple):
                 path_to_item=_path_to_item,
                 valid_classes=(self.__class__,),
             )
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):
+        """IntegerEnumWithDefaultValue - a model defined in OpenAPI
+
+        Note that value can be passed either in args or in kwargs, but not in both.
+
+        Args:
+            args[0] (int): if omitted defaults to 0, must be one of [0, 1, 2, ]  # noqa: E501
+
+        Keyword Args:
+            value (int): if omitted defaults to 0, must be one of [0, 1, 2, ]  # noqa: E501
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+        # required up here when default value is not given
+        _path_to_item = kwargs.pop('_path_to_item', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if 'value' in kwargs:
+            value = kwargs.pop('value')
+        elif args:
+            args = list(args)
+            value = args.pop(0)
+        else:
+            value = 0
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+        self.value = value
+        if kwargs:
+            raise ApiTypeError(
+                "Invalid named arguments=%s passed to %s. Remove those invalid named arguments." % (
+                    kwargs,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        return self

samples/openapi3/client/petstore/python/petstore_api/model/isosceles_triangle.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.shape_interface import ShapeInterface
@@ -100,6 +103,99 @@ class IsoscelesTriangle(ModelComposed):
         'triangle_type': 'triangleType',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """IsoscelesTriangle - a model defined in OpenAPI
+
+        Keyword Args:
+            shape_type (str):
+            triangle_type (str):
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        constant_args = {
+            '_check_type': _check_type,
+            '_path_to_item': _path_to_item,
+            '_spec_property_naming': _spec_property_naming,
+            '_configuration': _configuration,
+            '_visited_composed_classes': self._visited_composed_classes,
+        }
+        composed_info = validate_get_composed_info(
+            constant_args, kwargs, self)
+        self._composed_instances = composed_info[0]
+        self._var_name_to_model_instances = composed_info[1]
+        self._additional_properties_model_instances = composed_info[2]
+        discarded_args = composed_info[3]
+
+        for var_name, var_value in kwargs.items():
+            if var_name in discarded_args and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self._additional_properties_model_instances:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -196,6 +292,9 @@ class IsoscelesTriangle(ModelComposed):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")
 
     @cached_property
     def _composed_schemas():

samples/openapi3/client/petstore/python/petstore_api/model/list.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class List(ModelNormal):
@@ -90,8 +93,85 @@ class List(ModelNormal):
         '_123_list': '123-list',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """List - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            _123_list (str): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -170,3 +250,6 @@ class List(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/mammal.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.pig import Pig
@@ -118,6 +121,101 @@ class Mammal(ModelComposed):
         'type': 'type',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """Mammal - a model defined in OpenAPI
+
+        Keyword Args:
+            class_name (str):
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            has_baleen (bool): [optional]  # noqa: E501
+            has_teeth (bool): [optional]  # noqa: E501
+            type (str): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        constant_args = {
+            '_check_type': _check_type,
+            '_path_to_item': _path_to_item,
+            '_spec_property_naming': _spec_property_naming,
+            '_configuration': _configuration,
+            '_visited_composed_classes': self._visited_composed_classes,
+        }
+        composed_info = validate_get_composed_info(
+            constant_args, kwargs, self)
+        self._composed_instances = composed_info[0]
+        self._var_name_to_model_instances = composed_info[1]
+        self._additional_properties_model_instances = composed_info[2]
+        discarded_args = composed_info[3]
+
+        for var_name, var_value in kwargs.items():
+            if var_name in discarded_args and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self._additional_properties_model_instances:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -216,6 +314,9 @@ class Mammal(ModelComposed):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")
 
     @cached_property
     def _composed_schemas():

samples/openapi3/client/petstore/python/petstore_api/model/map_test.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.string_boolean_map import StringBooleanMap
@@ -106,8 +109,88 @@ class MapTest(ModelNormal):
         'indirect_map': 'indirect_map',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """MapTest - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            map_map_of_string ({str: ({str: (str,)},)}): [optional]  # noqa: E501
+            map_of_enum_string ({str: (str,)}): [optional]  # noqa: E501
+            direct_map ({str: (bool,)}): [optional]  # noqa: E501
+            indirect_map (StringBooleanMap): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -189,3 +272,6 @@ class MapTest(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/mixed_properties_and_additional_properties_class.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.animal import Animal
@@ -100,8 +103,87 @@ class MixedPropertiesAndAdditionalPropertiesClass(ModelNormal):
         'map': 'map',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """MixedPropertiesAndAdditionalPropertiesClass - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            uuid (str): [optional]  # noqa: E501
+            date_time (datetime): [optional]  # noqa: E501
+            map ({str: (Animal,)}): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -182,3 +264,6 @@ class MixedPropertiesAndAdditionalPropertiesClass(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/model200_response.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class Model200Response(ModelNormal):
@@ -92,8 +95,86 @@ class Model200Response(ModelNormal):
         '_class': 'class',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """Model200Response - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            name (int): [optional]  # noqa: E501
+            _class (str): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -173,3 +254,6 @@ class Model200Response(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/model_return.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class ModelReturn(ModelNormal):
@@ -90,8 +93,85 @@ class ModelReturn(ModelNormal):
         '_return': 'return',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """ModelReturn - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            _return (int): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -170,3 +250,6 @@ class ModelReturn(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/mole.py

@@ -0,0 +1,284 @@
+"""
+    OpenAPI Petstore
+
+    This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\  # noqa: E501
+
+    The version of the OpenAPI document: 1.0.0
+    Generated by: https://openapi-generator.tech
+"""
+
+
+import re  # noqa: F401
+import sys  # noqa: F401
+
+from petstore_api.model_utils import (  # noqa: F401
+    ApiTypeError,
+    ModelComposed,
+    ModelNormal,
+    ModelSimple,
+    cached_property,
+    change_keys_js_to_python,
+    convert_js_args_to_python_args,
+    date,
+    datetime,
+    file_type,
+    none_type,
+    validate_get_composed_info,
+)
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
+
+
+class Mole(ModelNormal):
+    """NOTE: This class is auto generated by OpenAPI Generator.
+    Ref: https://openapi-generator.tech
+
+    Do not edit the class manually.
+
+    Attributes:
+      allowed_values (dict): The key is the tuple path to the attribute
+          and the for var_name this is (var_name,). The value is a dict
+          with a capitalized key describing the allowed value and an allowed
+          value. These dicts store the allowed enum values.
+      attribute_map (dict): The key is attribute name
+          and the value is json key in definition.
+      discriminator_value_class_map (dict): A dict to go from the discriminator
+          variable value to the discriminator class name.
+      validations (dict): The key is the tuple path to the attribute
+          and the for var_name this is (var_name,). The value is a dict
+          that stores validations for max_length, min_length, max_items,
+          min_items, exclusive_maximum, inclusive_maximum, exclusive_minimum,
+          inclusive_minimum, and regex.
+      additional_properties_type (tuple): A tuple of classes accepted
+          as additional properties values.
+    """
+
+    allowed_values = {
+    }
+
+    validations = {
+    }
+
+    @cached_property
+    def additional_properties_type():
+        """
+        This must be a method because a model may have properties that are
+        of type self, this must run after the class is loaded
+        """
+        return (bool, date, datetime, dict, float, int, list, str, none_type,)  # noqa: E501
+
+    _nullable = False
+
+    @cached_property
+    def openapi_types():
+        """
+        This must be a method because a model may have properties that are
+        of type self, this must run after the class is loaded
+
+        Returns
+            openapi_types (dict): The key is attribute name
+                and the value is attribute type.
+        """
+        return {
+            'blind': (bool,),  # noqa: E501
+            'smell': (str,),  # noqa: E501
+            'hearing': (bool,),  # noqa: E501
+            'touch': (bool,),  # noqa: E501
+            'taste': (str,),  # noqa: E501
+            'seeing_ghosts': (bool,),  # noqa: E501
+        }
+
+    @cached_property
+    def discriminator():
+        return None
+
+
+    attribute_map = {
+        'blind': 'blind',  # noqa: E501
+        'smell': 'smell',  # noqa: E501
+        'hearing': 'hearing',  # noqa: E501
+        'touch': 'touch',  # noqa: E501
+        'taste': 'taste',  # noqa: E501
+        'seeing_ghosts': 'seeingGhosts',  # noqa: E501
+    }
+
+    read_only_vars = {
+        'blind',  # noqa: E501
+        'touch',  # noqa: E501
+    }
+
+    _composed_schemas = {}
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, blind, smell, hearing, *args, **kwargs):  # noqa: E501
+        """Mole - a model defined in OpenAPI
+
+        Args:
+            blind (bool):
+            smell (str):
+            hearing (bool):
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            touch (bool): [optional]  # noqa: E501
+            taste (str): [optional]  # noqa: E501
+            seeing_ghosts (bool): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        self.blind = blind
+        self.smell = smell
+        self.hearing = hearing
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
+    required_properties = set([
+        '_data_store',
+        '_check_type',
+        '_spec_property_naming',
+        '_path_to_item',
+        '_configuration',
+        '_visited_composed_classes',
+    ])
+
+    @convert_js_args_to_python_args
+    def __init__(self, smell, hearing, *args, **kwargs):  # noqa: E501
+        """Mole - a model defined in OpenAPI
+
+            smell (str):
+            hearing (bool):
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            touch (bool): [optional]  # noqa: E501
+            taste (str): [optional]  # noqa: E501
+            seeing_ghosts (bool): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        self.smell = smell
+        self.hearing = hearing
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/name.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class Name(ModelNormal):
@@ -96,8 +99,93 @@ class Name(ModelNormal):
         '_123_number': '123Number',  # noqa: E501
     }
 
+    read_only_vars = {
+        'snake_case',  # noqa: E501
+        '_123_number',  # noqa: E501
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, name, *args, **kwargs):  # noqa: E501
+        """Name - a model defined in OpenAPI
+
+        Args:
+            name (int):
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            snake_case (int): [optional]  # noqa: E501
+            _property (str): [optional]  # noqa: E501
+            _123_number (int): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        self.name = name
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -182,3 +270,6 @@ class Name(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/nullable_class.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class NullableClass(ModelNormal):
@@ -114,8 +117,97 @@ class NullableClass(ModelNormal):
         'object_items_nullable': 'object_items_nullable',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """NullableClass - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            integer_prop (int, none_type): [optional]  # noqa: E501
+            number_prop (float, none_type): [optional]  # noqa: E501
+            boolean_prop (bool, none_type): [optional]  # noqa: E501
+            string_prop (str, none_type): [optional]  # noqa: E501
+            date_prop (date, none_type): [optional]  # noqa: E501
+            datetime_prop (datetime, none_type): [optional]  # noqa: E501
+            array_nullable_prop ([{str: (bool, date, datetime, dict, float, int, list, str, none_type)}], none_type): [optional]  # noqa: E501
+            array_and_items_nullable_prop ([{str: (bool, date, datetime, dict, float, int, list, str, none_type)}, none_type], none_type): [optional]  # noqa: E501
+            array_items_nullable ([{str: (bool, date, datetime, dict, float, int, list, str, none_type)}, none_type]): [optional]  # noqa: E501
+            object_nullable ({str: (bool, date, datetime, dict, float, int, list, str, none_type)}, none_type): [optional]  # noqa: E501
+            object_nullable_prop ({str: ({str: (bool, date, datetime, dict, float, int, list, str, none_type)},)}, none_type): [optional]  # noqa: E501
+            object_and_items_nullable_prop ({str: ({str: (bool, date, datetime, dict, float, int, list, str, none_type)}, none_type)}, none_type): [optional]  # noqa: E501
+            object_items_nullable ({str: ({str: (bool, date, datetime, dict, float, int, list, str, none_type)}, none_type)}): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -206,3 +298,6 @@ class NullableClass(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/nullable_shape.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.quadrilateral import Quadrilateral
@@ -108,6 +111,100 @@ class NullableShape(ModelComposed):
         'triangle_type': 'triangleType',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """NullableShape - a model defined in OpenAPI
+
+        Keyword Args:
+            shape_type (str):
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            quadrilateral_type (str): [optional]  # noqa: E501
+            triangle_type (str): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        constant_args = {
+            '_check_type': _check_type,
+            '_path_to_item': _path_to_item,
+            '_spec_property_naming': _spec_property_naming,
+            '_configuration': _configuration,
+            '_visited_composed_classes': self._visited_composed_classes,
+        }
+        composed_info = validate_get_composed_info(
+            constant_args, kwargs, self)
+        self._composed_instances = composed_info[0]
+        self._var_name_to_model_instances = composed_info[1]
+        self._additional_properties_model_instances = composed_info[2]
+        discarded_args = composed_info[3]
+
+        for var_name, var_value in kwargs.items():
+            if var_name in discarded_args and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self._additional_properties_model_instances:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -205,6 +302,9 @@ class NullableShape(ModelComposed):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")
 
     @cached_property
     def _composed_schemas():

samples/openapi3/client/petstore/python/petstore_api/model/number_only.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class NumberOnly(ModelNormal):
@@ -90,8 +93,85 @@ class NumberOnly(ModelNormal):
         'just_number': 'JustNumber',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """NumberOnly - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            just_number (float): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -170,3 +250,6 @@ class NumberOnly(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/number_with_validations.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class NumberWithValidations(ModelSimple):
@@ -88,6 +91,8 @@ class NumberWithValidations(ModelSimple):
 
     attribute_map = {}
 
+    read_only_vars = set()
+
     _composed_schemas = None
 
     required_properties = set([
@@ -187,3 +192,97 @@ class NumberWithValidations(ModelSimple):
                 path_to_item=_path_to_item,
                 valid_classes=(self.__class__,),
             )
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):
+        """NumberWithValidations - a model defined in OpenAPI
+
+        Note that value can be passed either in args or in kwargs, but not in both.
+
+        Args:
+            args[0] (float):  # noqa: E501
+
+        Keyword Args:
+            value (float):  # noqa: E501
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+        # required up here when default value is not given
+        _path_to_item = kwargs.pop('_path_to_item', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if 'value' in kwargs:
+            value = kwargs.pop('value')
+        elif args:
+            args = list(args)
+            value = args.pop(0)
+        else:
+            raise ApiTypeError(
+                "value is required, but not passed in args or kwargs and doesn't have default",
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+        self.value = value
+        if kwargs:
+            raise ApiTypeError(
+                "Invalid named arguments=%s passed to %s. Remove those invalid named arguments." % (
+                    kwargs,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        return self

samples/openapi3/client/petstore/python/petstore_api/model/object_interface.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class ObjectInterface(ModelNormal):
@@ -88,8 +91,84 @@ class ObjectInterface(ModelNormal):
     attribute_map = {
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """ObjectInterface - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -167,3 +246,6 @@ class ObjectInterface(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/object_model_with_ref_props.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.number_with_validations import NumberWithValidations
@@ -104,8 +107,88 @@ class ObjectModelWithRefProps(ModelNormal):
         'my_boolean': 'my_boolean',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """ObjectModelWithRefProps - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            my_number (NumberWithValidations): [optional]  # noqa: E501
+            my_readonly (Readonly): [optional]  # noqa: E501
+            my_string (str): [optional]  # noqa: E501
+            my_boolean (bool): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -187,3 +270,6 @@ class ObjectModelWithRefProps(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/object_with_validations.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class ObjectWithValidations(ModelNormal):
@@ -91,8 +94,84 @@ class ObjectWithValidations(ModelNormal):
     attribute_map = {
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """ObjectWithValidations - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -170,3 +249,6 @@ class ObjectWithValidations(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/order.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class Order(ModelNormal):
@@ -105,8 +108,90 @@ class Order(ModelNormal):
         'complete': 'complete',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """Order - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            id (int): [optional]  # noqa: E501
+            pet_id (int): [optional]  # noqa: E501
+            quantity (int): [optional]  # noqa: E501
+            ship_date (datetime): [optional]  # noqa: E501
+            status (str): Order Status. [optional]  # noqa: E501
+            complete (bool): [optional] if omitted the server will use the default value of False  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -190,3 +275,6 @@ class Order(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/parent_pet.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.child_cat import ChildCat
@@ -103,6 +106,98 @@ class ParentPet(ModelComposed):
         'pet_type': 'pet_type',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """ParentPet - a model defined in OpenAPI
+
+        Keyword Args:
+            pet_type (str):
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        constant_args = {
+            '_check_type': _check_type,
+            '_path_to_item': _path_to_item,
+            '_spec_property_naming': _spec_property_naming,
+            '_configuration': _configuration,
+            '_visited_composed_classes': self._visited_composed_classes,
+        }
+        composed_info = validate_get_composed_info(
+            constant_args, kwargs, self)
+        self._composed_instances = composed_info[0]
+        self._var_name_to_model_instances = composed_info[1]
+        self._additional_properties_model_instances = composed_info[2]
+        discarded_args = composed_info[3]
+
+        for var_name, var_value in kwargs.items():
+            if var_name in discarded_args and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self._additional_properties_model_instances:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -198,6 +293,9 @@ class ParentPet(ModelComposed):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")
 
     @cached_property
     def _composed_schemas():

samples/openapi3/client/petstore/python/petstore_api/model/pet.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.category import Category
@@ -113,8 +116,94 @@ class Pet(ModelNormal):
         'status': 'status',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, name, photo_urls, *args, **kwargs):  # noqa: E501
+        """Pet - a model defined in OpenAPI
+
+        Args:
+            name (str):
+            photo_urls ([str]):
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            id (int): [optional]  # noqa: E501
+            category (Category): [optional]  # noqa: E501
+            tags ([Tag]): [optional]  # noqa: E501
+            status (str): pet status in the store. [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        self.name = name
+        self.photo_urls = photo_urls
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -202,3 +291,6 @@ class Pet(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/pig.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.basque_pig import BasquePig
@@ -104,6 +107,98 @@ class Pig(ModelComposed):
         'class_name': 'className',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """Pig - a model defined in OpenAPI
+
+        Keyword Args:
+            class_name (str):
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        constant_args = {
+            '_check_type': _check_type,
+            '_path_to_item': _path_to_item,
+            '_spec_property_naming': _spec_property_naming,
+            '_configuration': _configuration,
+            '_visited_composed_classes': self._visited_composed_classes,
+        }
+        composed_info = validate_get_composed_info(
+            constant_args, kwargs, self)
+        self._composed_instances = composed_info[0]
+        self._var_name_to_model_instances = composed_info[1]
+        self._additional_properties_model_instances = composed_info[2]
+        discarded_args = composed_info[3]
+
+        for var_name, var_value in kwargs.items():
+            if var_name in discarded_args and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self._additional_properties_model_instances:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -199,6 +294,9 @@ class Pig(ModelComposed):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")
 
     @cached_property
     def _composed_schemas():

samples/openapi3/client/petstore/python/petstore_api/model/quadrilateral.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.complex_quadrilateral import ComplexQuadrilateral
@@ -106,6 +109,99 @@ class Quadrilateral(ModelComposed):
         'shape_type': 'shapeType',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """Quadrilateral - a model defined in OpenAPI
+
+        Keyword Args:
+            quadrilateral_type (str):
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            shape_type (str): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        constant_args = {
+            '_check_type': _check_type,
+            '_path_to_item': _path_to_item,
+            '_spec_property_naming': _spec_property_naming,
+            '_configuration': _configuration,
+            '_visited_composed_classes': self._visited_composed_classes,
+        }
+        composed_info = validate_get_composed_info(
+            constant_args, kwargs, self)
+        self._composed_instances = composed_info[0]
+        self._var_name_to_model_instances = composed_info[1]
+        self._additional_properties_model_instances = composed_info[2]
+        discarded_args = composed_info[3]
+
+        for var_name, var_value in kwargs.items():
+            if var_name in discarded_args and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self._additional_properties_model_instances:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -202,6 +298,9 @@ class Quadrilateral(ModelComposed):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")
 
     @cached_property
     def _composed_schemas():

samples/openapi3/client/petstore/python/petstore_api/model/quadrilateral_interface.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class QuadrilateralInterface(ModelNormal):
@@ -90,8 +93,88 @@ class QuadrilateralInterface(ModelNormal):
         'quadrilateral_type': 'quadrilateralType',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, quadrilateral_type, *args, **kwargs):  # noqa: E501
+        """QuadrilateralInterface - a model defined in OpenAPI
+
+        Args:
+            quadrilateral_type (str):
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        self.quadrilateral_type = quadrilateral_type
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -173,3 +256,6 @@ class QuadrilateralInterface(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/read_only_first.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class ReadOnlyFirst(ModelNormal):
@@ -92,8 +95,87 @@ class ReadOnlyFirst(ModelNormal):
         'baz': 'baz',  # noqa: E501
     }
 
+    read_only_vars = {
+        'bar',  # noqa: E501
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """ReadOnlyFirst - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            bar (str): [optional]  # noqa: E501
+            baz (str): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -173,3 +255,6 @@ class ReadOnlyFirst(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/readonly.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class Readonly(ModelNormal):
@@ -90,8 +93,85 @@ class Readonly(ModelNormal):
         'name': 'name',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """Readonly - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            name (str): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -170,3 +250,6 @@ class Readonly(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/scalene_triangle.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.shape_interface import ShapeInterface
@@ -100,6 +103,99 @@ class ScaleneTriangle(ModelComposed):
         'triangle_type': 'triangleType',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """ScaleneTriangle - a model defined in OpenAPI
+
+        Keyword Args:
+            shape_type (str):
+            triangle_type (str):
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        constant_args = {
+            '_check_type': _check_type,
+            '_path_to_item': _path_to_item,
+            '_spec_property_naming': _spec_property_naming,
+            '_configuration': _configuration,
+            '_visited_composed_classes': self._visited_composed_classes,
+        }
+        composed_info = validate_get_composed_info(
+            constant_args, kwargs, self)
+        self._composed_instances = composed_info[0]
+        self._var_name_to_model_instances = composed_info[1]
+        self._additional_properties_model_instances = composed_info[2]
+        discarded_args = composed_info[3]
+
+        for var_name, var_value in kwargs.items():
+            if var_name in discarded_args and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self._additional_properties_model_instances:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -196,6 +292,9 @@ class ScaleneTriangle(ModelComposed):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")
 
     @cached_property
     def _composed_schemas():

samples/openapi3/client/petstore/python/petstore_api/model/shape.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.quadrilateral import Quadrilateral
@@ -108,6 +111,100 @@ class Shape(ModelComposed):
         'triangle_type': 'triangleType',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """Shape - a model defined in OpenAPI
+
+        Keyword Args:
+            shape_type (str):
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            quadrilateral_type (str): [optional]  # noqa: E501
+            triangle_type (str): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        constant_args = {
+            '_check_type': _check_type,
+            '_path_to_item': _path_to_item,
+            '_spec_property_naming': _spec_property_naming,
+            '_configuration': _configuration,
+            '_visited_composed_classes': self._visited_composed_classes,
+        }
+        composed_info = validate_get_composed_info(
+            constant_args, kwargs, self)
+        self._composed_instances = composed_info[0]
+        self._var_name_to_model_instances = composed_info[1]
+        self._additional_properties_model_instances = composed_info[2]
+        discarded_args = composed_info[3]
+
+        for var_name, var_value in kwargs.items():
+            if var_name in discarded_args and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self._additional_properties_model_instances:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -205,6 +302,9 @@ class Shape(ModelComposed):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")
 
     @cached_property
     def _composed_schemas():

samples/openapi3/client/petstore/python/petstore_api/model/shape_interface.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class ShapeInterface(ModelNormal):
@@ -90,8 +93,88 @@ class ShapeInterface(ModelNormal):
         'shape_type': 'shapeType',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, shape_type, *args, **kwargs):  # noqa: E501
+        """ShapeInterface - a model defined in OpenAPI
+
+        Args:
+            shape_type (str):
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        self.shape_type = shape_type
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -173,3 +256,6 @@ class ShapeInterface(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/shape_or_null.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.quadrilateral import Quadrilateral
@@ -108,6 +111,100 @@ class ShapeOrNull(ModelComposed):
         'triangle_type': 'triangleType',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """ShapeOrNull - a model defined in OpenAPI
+
+        Keyword Args:
+            shape_type (str):
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            quadrilateral_type (str): [optional]  # noqa: E501
+            triangle_type (str): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        constant_args = {
+            '_check_type': _check_type,
+            '_path_to_item': _path_to_item,
+            '_spec_property_naming': _spec_property_naming,
+            '_configuration': _configuration,
+            '_visited_composed_classes': self._visited_composed_classes,
+        }
+        composed_info = validate_get_composed_info(
+            constant_args, kwargs, self)
+        self._composed_instances = composed_info[0]
+        self._var_name_to_model_instances = composed_info[1]
+        self._additional_properties_model_instances = composed_info[2]
+        discarded_args = composed_info[3]
+
+        for var_name, var_value in kwargs.items():
+            if var_name in discarded_args and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self._additional_properties_model_instances:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -205,6 +302,9 @@ class ShapeOrNull(ModelComposed):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")
 
     @cached_property
     def _composed_schemas():

samples/openapi3/client/petstore/python/petstore_api/model/simple_quadrilateral.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.quadrilateral_interface import QuadrilateralInterface
@@ -100,6 +103,99 @@ class SimpleQuadrilateral(ModelComposed):
         'quadrilateral_type': 'quadrilateralType',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """SimpleQuadrilateral - a model defined in OpenAPI
+
+        Keyword Args:
+            shape_type (str):
+            quadrilateral_type (str):
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        constant_args = {
+            '_check_type': _check_type,
+            '_path_to_item': _path_to_item,
+            '_spec_property_naming': _spec_property_naming,
+            '_configuration': _configuration,
+            '_visited_composed_classes': self._visited_composed_classes,
+        }
+        composed_info = validate_get_composed_info(
+            constant_args, kwargs, self)
+        self._composed_instances = composed_info[0]
+        self._var_name_to_model_instances = composed_info[1]
+        self._additional_properties_model_instances = composed_info[2]
+        discarded_args = composed_info[3]
+
+        for var_name, var_value in kwargs.items():
+            if var_name in discarded_args and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self._additional_properties_model_instances:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -196,6 +292,9 @@ class SimpleQuadrilateral(ModelComposed):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")
 
     @cached_property
     def _composed_schemas():

samples/openapi3/client/petstore/python/petstore_api/model/some_object.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.object_interface import ObjectInterface
@@ -94,6 +97,97 @@ class SomeObject(ModelComposed):
     attribute_map = {
     }
 
+    read_only_vars = {
+    }
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """SomeObject - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        constant_args = {
+            '_check_type': _check_type,
+            '_path_to_item': _path_to_item,
+            '_spec_property_naming': _spec_property_naming,
+            '_configuration': _configuration,
+            '_visited_composed_classes': self._visited_composed_classes,
+        }
+        composed_info = validate_get_composed_info(
+            constant_args, kwargs, self)
+        self._composed_instances = composed_info[0]
+        self._var_name_to_model_instances = composed_info[1]
+        self._additional_properties_model_instances = composed_info[2]
+        discarded_args = composed_info[3]
+
+        for var_name, var_value in kwargs.items():
+            if var_name in discarded_args and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self._additional_properties_model_instances:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -188,6 +282,9 @@ class SomeObject(ModelComposed):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")
 
     @cached_property
     def _composed_schemas():

samples/openapi3/client/petstore/python/petstore_api/model/some_object_with_self_attr.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class SomeObjectWithSelfAttr(ModelNormal):
@@ -90,8 +93,85 @@ class SomeObjectWithSelfAttr(ModelNormal):
         '_self': 'self',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """SomeObjectWithSelfAttr - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            _self (str): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -170,3 +250,6 @@ class SomeObjectWithSelfAttr(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/special_model_name.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class SpecialModelName(ModelNormal):
@@ -90,8 +93,85 @@ class SpecialModelName(ModelNormal):
         'special_property_name': '$special[property.name]',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """SpecialModelName - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            special_property_name (int): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -170,3 +250,6 @@ class SpecialModelName(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/string_boolean_map.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class StringBooleanMap(ModelNormal):
@@ -88,8 +91,84 @@ class StringBooleanMap(ModelNormal):
     attribute_map = {
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """StringBooleanMap - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -167,3 +246,6 @@ class StringBooleanMap(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/string_enum.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class StringEnum(ModelSimple):
@@ -95,6 +98,8 @@ lines''',
 
     attribute_map = {}
 
+    read_only_vars = set()
+
     _composed_schemas = None
 
     required_properties = set([
@@ -198,3 +203,101 @@ lines''', '''double quote
                 path_to_item=_path_to_item,
                 valid_classes=(self.__class__,),
             )
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):
+        """StringEnum - a model defined in OpenAPI
+
+        Note that value can be passed either in args or in kwargs, but not in both.
+
+        Args:
+            args[0] (str):, must be one of ["placed", "approved", "delivered", "single quoted", '''multiple
+lines''', '''double quote 
+ with newline''', ]  # noqa: E501
+
+        Keyword Args:
+            value (str):, must be one of ["placed", "approved", "delivered", "single quoted", '''multiple
+lines''', '''double quote 
+ with newline''', ]  # noqa: E501
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+        # required up here when default value is not given
+        _path_to_item = kwargs.pop('_path_to_item', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if 'value' in kwargs:
+            value = kwargs.pop('value')
+        elif args:
+            args = list(args)
+            value = args.pop(0)
+        else:
+            raise ApiTypeError(
+                "value is required, but not passed in args or kwargs and doesn't have default",
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+        self.value = value
+        if kwargs:
+            raise ApiTypeError(
+                "Invalid named arguments=%s passed to %s. Remove those invalid named arguments." % (
+                    kwargs,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        return self

samples/openapi3/client/petstore/python/petstore_api/model/string_enum_with_default_value.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class StringEnumWithDefaultValue(ModelSimple):
@@ -89,6 +92,8 @@ class StringEnumWithDefaultValue(ModelSimple):
 
     attribute_map = {}
 
+    read_only_vars = set()
+
     _composed_schemas = None
 
     required_properties = set([
@@ -184,3 +189,93 @@ class StringEnumWithDefaultValue(ModelSimple):
                 path_to_item=_path_to_item,
                 valid_classes=(self.__class__,),
             )
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):
+        """StringEnumWithDefaultValue - a model defined in OpenAPI
+
+        Note that value can be passed either in args or in kwargs, but not in both.
+
+        Args:
+            args[0] (str): if omitted defaults to "placed", must be one of ["placed", "approved", "delivered", ]  # noqa: E501
+
+        Keyword Args:
+            value (str): if omitted defaults to "placed", must be one of ["placed", "approved", "delivered", ]  # noqa: E501
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+        # required up here when default value is not given
+        _path_to_item = kwargs.pop('_path_to_item', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if 'value' in kwargs:
+            value = kwargs.pop('value')
+        elif args:
+            args = list(args)
+            value = args.pop(0)
+        else:
+            value = "placed"
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+        self.value = value
+        if kwargs:
+            raise ApiTypeError(
+                "Invalid named arguments=%s passed to %s. Remove those invalid named arguments." % (
+                    kwargs,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        return self

samples/openapi3/client/petstore/python/petstore_api/model/tag.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class Tag(ModelNormal):
@@ -92,8 +95,86 @@ class Tag(ModelNormal):
         'name': 'name',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """Tag - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            id (int): [optional]  # noqa: E501
+            name (str): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -173,3 +254,6 @@ class Tag(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/triangle.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 def lazy_import():
     from petstore_api.model.equilateral_triangle import EquilateralTriangle
@@ -109,6 +112,99 @@ class Triangle(ModelComposed):
         'shape_type': 'shapeType',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """Triangle - a model defined in OpenAPI
+
+        Keyword Args:
+            triangle_type (str):
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            shape_type (str): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        constant_args = {
+            '_check_type': _check_type,
+            '_path_to_item': _path_to_item,
+            '_spec_property_naming': _spec_property_naming,
+            '_configuration': _configuration,
+            '_visited_composed_classes': self._visited_composed_classes,
+        }
+        composed_info = validate_get_composed_info(
+            constant_args, kwargs, self)
+        self._composed_instances = composed_info[0]
+        self._var_name_to_model_instances = composed_info[1]
+        self._additional_properties_model_instances = composed_info[2]
+        discarded_args = composed_info[3]
+
+        for var_name, var_value in kwargs.items():
+            if var_name in discarded_args and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self._additional_properties_model_instances:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -205,6 +301,9 @@ class Triangle(ModelComposed):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")
 
     @cached_property
     def _composed_schemas():

samples/openapi3/client/petstore/python/petstore_api/model/triangle_interface.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class TriangleInterface(ModelNormal):
@@ -90,8 +93,88 @@ class TriangleInterface(ModelNormal):
         'triangle_type': 'triangleType',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, triangle_type, *args, **kwargs):  # noqa: E501
+        """TriangleInterface - a model defined in OpenAPI
+
+        Args:
+            triangle_type (str):
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        self.triangle_type = triangle_type
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -173,3 +256,6 @@ class TriangleInterface(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/user.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class User(ModelNormal):
@@ -112,8 +115,96 @@ class User(ModelNormal):
         'any_type_prop_nullable': 'anyTypePropNullable',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, *args, **kwargs):  # noqa: E501
+        """User - a model defined in OpenAPI
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            id (int): [optional]  # noqa: E501
+            username (str): [optional]  # noqa: E501
+            first_name (str): [optional]  # noqa: E501
+            last_name (str): [optional]  # noqa: E501
+            email (str): [optional]  # noqa: E501
+            password (str): [optional]  # noqa: E501
+            phone (str): [optional]  # noqa: E501
+            user_status (int): User Status. [optional]  # noqa: E501
+            object_with_no_declared_props ({str: (bool, date, datetime, dict, float, int, list, str, none_type)}): test code generation for objects Value must be a map of strings to values. It cannot be the 'null' value.. [optional]  # noqa: E501
+            object_with_no_declared_props_nullable ({str: (bool, date, datetime, dict, float, int, list, str, none_type)}, none_type): test code generation for nullable objects. Value must be a map of strings to values or the 'null' value.. [optional]  # noqa: E501
+            any_type_prop (bool, date, datetime, dict, float, int, list, str, none_type): test code generation for any type Here the 'type' attribute is not specified, which means the value can be anything, including the null value, string, number, boolean, array or object. See https://github.com/OAI/OpenAPI-Specification/issues/1389. [optional]  # noqa: E501
+            any_type_prop_nullable (bool, date, datetime, dict, float, int, list, str, none_type): test code generation for any type Here the 'type' attribute is not specified, which means the value can be anything, including the null value, string, number, boolean, array or object. The 'nullable' attribute does not change the allowed values.. [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -203,3 +294,6 @@ class User(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/whale.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class Whale(ModelNormal):
@@ -94,8 +97,90 @@ class Whale(ModelNormal):
         'has_teeth': 'hasTeeth',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, class_name, *args, **kwargs):  # noqa: E501
+        """Whale - a model defined in OpenAPI
+
+        Args:
+            class_name (str):
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            has_baleen (bool): [optional]  # noqa: E501
+            has_teeth (bool): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        self.class_name = class_name
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -179,3 +264,6 @@ class Whale(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model/zebra.py

@@ -25,6 +25,9 @@ from petstore_api.model_utils import (  # noqa: F401
     none_type,
     validate_get_composed_info,
 )
+from ..model_utils import OpenApiModel
+from petstore_api.exceptions import ApiAttributeError
+
 
 
 class Zebra(ModelNormal):
@@ -97,8 +100,89 @@ class Zebra(ModelNormal):
         'type': 'type',  # noqa: E501
     }
 
+    read_only_vars = {
+    }
+
     _composed_schemas = {}
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _from_openapi_data(cls, class_name, *args, **kwargs):  # noqa: E501
+        """Zebra - a model defined in OpenAPI
+
+        Args:
+            class_name (str):
+
+        Keyword Args:
+            _check_type (bool): if True, values for parameters in openapi_types
+                                will be type checked and a TypeError will be
+                                raised if the wrong type is input.
+                                Defaults to True
+            _path_to_item (tuple/list): This is a list of keys or values to
+                                drill down to the model in received_data
+                                when deserializing a response
+            _spec_property_naming (bool): True if the variable names in the input data
+                                are serialized names, as specified in the OpenAPI document.
+                                False if the variable names in the input data
+                                are pythonic names, e.g. snake case (default)
+            _configuration (Configuration): the instance to use when
+                                deserializing a file_type parameter.
+                                If passed, type conversion is attempted
+                                If omitted no type conversion is done.
+            _visited_composed_classes (tuple): This stores a tuple of
+                                classes that we have traveled through so that
+                                if we see that class again we will not use its
+                                discriminator again.
+                                When traveling through a discriminator, the
+                                composed schema that is
+                                is traveled through is added to this set.
+                                For example if Animal has a discriminator
+                                petType and we pass in "Dog", and the class Dog
+                                allOf includes Animal, we move through Animal
+                                once using the discriminator, and pick Dog.
+                                Then in Dog, we will make an instance of the
+                                Animal class but this time we won't travel
+                                through its discriminator because we passed in
+                                _visited_composed_classes = (Animal,)
+            type (str): [optional]  # noqa: E501
+        """
+
+        _check_type = kwargs.pop('_check_type', True)
+        _spec_property_naming = kwargs.pop('_spec_property_naming', False)
+        _path_to_item = kwargs.pop('_path_to_item', ())
+        _configuration = kwargs.pop('_configuration', None)
+        _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
+
+        self = super(OpenApiModel, cls).__new__(cls)
+
+        if args:
+            raise ApiTypeError(
+                "Invalid positional arguments=%s passed to %s. Remove those invalid positional arguments." % (
+                    args,
+                    self.__class__.__name__,
+                ),
+                path_to_item=_path_to_item,
+                valid_classes=(self.__class__,),
+            )
+
+        self._data_store = {}
+        self._check_type = _check_type
+        self._spec_property_naming = _spec_property_naming
+        self._path_to_item = _path_to_item
+        self._configuration = _configuration
+        self._visited_composed_classes = _visited_composed_classes + (self.__class__,)
+
+        self.class_name = class_name
+        for var_name, var_value in kwargs.items():
+            if var_name not in self.attribute_map and \
+                        self._configuration is not None and \
+                        self._configuration.discard_unknown_keys and \
+                        self.additional_properties_type is None:
+                # discard variable.
+                continue
+            setattr(self, var_name, var_value)
+        return self
+
     required_properties = set([
         '_data_store',
         '_check_type',
@@ -181,3 +265,6 @@ class Zebra(ModelNormal):
                 # discard variable.
                 continue
             setattr(self, var_name, var_value)
+            if var_name in self.read_only_vars:
+                raise ApiAttributeError(f"`{var_name}` is a read-only attribute. Use `from_openapi_data` to instantiate "
+                                     f"class with read only attributes.")

samples/openapi3/client/petstore/python/petstore_api/model_utils.py

@@ -29,6 +29,22 @@ none_type = type(None)
 file_type = io.IOBase
 
 
+def convert_js_args_to_python_args(fn):
+    from functools import wraps
+    @wraps(fn)
+    def wrapped_init(_self, *args, **kwargs):
+        """
+        An attribute named `self` received from the api will conflicts with the reserved `self`
+        parameter of a class method. During generation, `self` attributes are mapped
+        to `_self` in models. Here, we name `_self` instead of `self` to avoid conflicts.
+        """
+        spec_property_naming = kwargs.get('_spec_property_naming', False)
+        if spec_property_naming:
+            kwargs = change_keys_js_to_python(kwargs, _self if isinstance(_self, type) else _self.__class__)
+        return fn(_self, *args, **kwargs)
+    return wrapped_init
+
+
 class cached_property(object):
     # this caches the result of the function call for fn with no inputs
     # use this as a decorator on fuction methods that you want converted
@@ -284,6 +300,121 @@ class OpenApiModel(object):
         return new_inst
 
 
+    @classmethod
+    @convert_js_args_to_python_args
+    def _new_from_openapi_data(cls, *args, **kwargs):
+        # this function uses the discriminator to
+        # pick a new schema/class to instantiate because a discriminator
+        # propertyName value was passed in
+
+        if len(args) == 1:
+            arg = args[0]
+            if arg is None and is_type_nullable(cls):
+                # The input data is the 'null' value and the type is nullable.
+                return None
+
+            if issubclass(cls, ModelComposed) and allows_single_value_input(cls):
+                model_kwargs = {}
+                oneof_instance = get_oneof_instance(cls, model_kwargs, kwargs, model_arg=arg)
+                return oneof_instance
+
+
+        visited_composed_classes = kwargs.get('_visited_composed_classes', ())
+        if (
+            cls.discriminator is None or
+            cls in visited_composed_classes
+        ):
+            # Use case 1: this openapi schema (cls) does not have a discriminator
+            # Use case 2: we have already visited this class before and are sure that we
+            # want to instantiate it this time. We have visited this class deserializing
+            # a payload with a discriminator. During that process we traveled through
+            # this class but did not make an instance of it. Now we are making an
+            # instance of a composed class which contains cls in it, so this time make an instance of cls.
+            #
+            # Here's an example of use case 2: If Animal has a discriminator
+            # petType and we pass in "Dog", and the class Dog
+            # allOf includes Animal, we move through Animal
+            # once using the discriminator, and pick Dog.
+            # Then in the composed schema dog Dog, we will make an instance of the
+            # Animal class (because Dal has allOf: Animal) but this time we won't travel
+            # through Animal's discriminator because we passed in
+            # _visited_composed_classes = (Animal,)
+
+            return cls._from_openapi_data(*args, **kwargs)
+
+        # Get the name and value of the discriminator property.
+        # The discriminator name is obtained from the discriminator meta-data
+        # and the discriminator value is obtained from the input data.
+        discr_propertyname_py = list(cls.discriminator.keys())[0]
+        discr_propertyname_js = cls.attribute_map[discr_propertyname_py]
+        if discr_propertyname_js in kwargs:
+            discr_value = kwargs[discr_propertyname_js]
+        elif discr_propertyname_py in kwargs:
+            discr_value = kwargs[discr_propertyname_py]
+        else:
+            # The input data does not contain the discriminator property.
+            path_to_item = kwargs.get('_path_to_item', ())
+            raise ApiValueError(
+                "Cannot deserialize input data due to missing discriminator. "
+                "The discriminator property '%s' is missing at path: %s" %
+                (discr_propertyname_js, path_to_item)
+            )
+
+        # Implementation note: the last argument to get_discriminator_class
+        # is a list of visited classes. get_discriminator_class may recursively
+        # call itself and update the list of visited classes, and the initial
+        # value must be an empty list. Hence not using 'visited_composed_classes'
+        new_cls = get_discriminator_class(
+                    cls, discr_propertyname_py, discr_value, [])
+        if new_cls is None:
+            path_to_item = kwargs.get('_path_to_item', ())
+            disc_prop_value = kwargs.get(
+                discr_propertyname_js, kwargs.get(discr_propertyname_py))
+            raise ApiValueError(
+                "Cannot deserialize input data due to invalid discriminator "
+                "value. The OpenAPI document has no mapping for discriminator "
+                "property '%s'='%s' at path: %s" %
+                (discr_propertyname_js, disc_prop_value, path_to_item)
+            )
+
+        if new_cls in visited_composed_classes:
+            # if we are making an instance of a composed schema Descendent
+            # which allOf includes Ancestor, then Ancestor contains
+            # a discriminator that includes Descendent.
+            # So if we make an instance of Descendent, we have to make an
+            # instance of Ancestor to hold the allOf properties.
+            # This code detects that use case and makes the instance of Ancestor
+            # For example:
+            # When making an instance of Dog, _visited_composed_classes = (Dog,)
+            # then we make an instance of Animal to include in dog._composed_instances
+            # so when we are here, cls is Animal
+            # cls.discriminator != None
+            # cls not in _visited_composed_classes
+            # new_cls = Dog
+            # but we know we know that we already have Dog
+            # because it is in visited_composed_classes
+            # so make Animal here
+            return cls._from_openapi_data(*args, **kwargs)
+
+        # Build a list containing all oneOf and anyOf descendants.
+        oneof_anyof_classes = None
+        if cls._composed_schemas is not None:
+            oneof_anyof_classes = (
+                cls._composed_schemas.get('oneOf', ()) +
+                cls._composed_schemas.get('anyOf', ()))
+        oneof_anyof_child = new_cls in oneof_anyof_classes
+        kwargs['_visited_composed_classes'] = visited_composed_classes + (cls,)
+
+        if cls._composed_schemas.get('allOf') and oneof_anyof_child:
+            # Validate that we can make self because when we make the
+            # new_cls it will not include the allOf validations in self
+            self_inst = cls._from_openapi_data(*args, **kwargs)
+
+
+        new_inst = new_cls._new_from_openapi_data(*args, **kwargs)
+        return new_inst
+
+
 class ModelSimple(OpenApiModel):
     """the parent class of models whose type != object in their
     swagger/openapi"""
@@ -1208,14 +1339,14 @@ def deserialize_model(model_data, model_class, path_to_item, check_type,
                    _spec_property_naming=spec_property_naming)
 
     if issubclass(model_class, ModelSimple):
-        return model_class(model_data, **kw_args)
+        return model_class._new_from_openapi_data(model_data, **kw_args)
     elif isinstance(model_data, list):
-        return model_class(*model_data, **kw_args)
+        return model_class._new_from_openapi_data(*model_data, **kw_args)
     if isinstance(model_data, dict):
         kw_args.update(model_data)
-        return model_class(**kw_args)
+        return model_class._new_from_openapi_data(**kw_args)
     elif isinstance(model_data, PRIMITIVE_TYPES):
-        return model_class(model_data, **kw_args)
+        return model_class._new_from_openapi_data(model_data, **kw_args)
 
 
 def deserialize_file(response_data, configuration, content_disposition=None):
@@ -1577,22 +1708,6 @@ def get_valid_classes_phrase(input_classes):
     return "is one of [{0}]".format(", ".join(all_class_names))
 
 
-def convert_js_args_to_python_args(fn):
-    from functools import wraps
-    @wraps(fn)
-    def wrapped_init(_self, *args, **kwargs):
-        """
-        An attribute named `self` received from the api will conflicts with the reserved `self`
-        parameter of a class method. During generation, `self` attributes are mapped
-        to `_self` in models. Here, we name `_self` instead of `self` to avoid conflicts.
-        """
-        spec_property_naming = kwargs.get('_spec_property_naming', False)
-        if spec_property_naming:
-            kwargs = change_keys_js_to_python(kwargs, _self.__class__)
-        return fn(_self, *args, **kwargs)
-    return wrapped_init
-
-
 def get_allof_instances(self, model_args, constant_args):
     """
     Args:

samples/openapi3/client/petstore/python/petstore_api/models/__init__.py

@@ -67,6 +67,7 @@ from petstore_api.model.map_test import MapTest
 from petstore_api.model.mixed_properties_and_additional_properties_class import MixedPropertiesAndAdditionalPropertiesClass
 from petstore_api.model.model200_response import Model200Response
 from petstore_api.model.model_return import ModelReturn
+from petstore_api.model.mole import Mole
 from petstore_api.model.name import Name
 from petstore_api.model.nullable_class import NullableClass
 from petstore_api.model.nullable_shape import NullableShape

samples/openapi3/client/petstore/python/test/test_mole.py

@@ -0,0 +1,35 @@
+"""
+    OpenAPI Petstore
+
+    This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\  # noqa: E501
+
+    The version of the OpenAPI document: 1.0.0
+    Generated by: https://openapi-generator.tech
+"""
+
+
+import sys
+import unittest
+
+import petstore_api
+from petstore_api.model.mole import Mole
+
+
+class TestMole(unittest.TestCase):
+    """Mole unit test stubs"""
+
+    def setUp(self):
+        pass
+
+    def tearDown(self):
+        pass
+
+    def testMole(self):
+        """Test Mole"""
+        # FIXME: construct object with mandatory attributes with example values
+        # mole = Mole()  # noqa: E501
+        pass
+
+
+if __name__ == '__main__':
+    unittest.main()

samples/openapi3/client/petstore/python/tests_manual/test_mole.py

@@ -0,0 +1,78 @@
+# coding: utf-8
+
+"""
+    OpenAPI Petstore
+
+    This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\  # noqa: E501
+
+    The version of the OpenAPI document: 1.0.0
+    Generated by: https://openapi-generator.tech
+"""
+
+
+import sys
+import unittest
+from petstore_api.exceptions import ApiAttributeError
+
+import petstore_api
+
+try:
+    from petstore_api.model import mole
+except ImportError:
+    mole = sys.modules["petstore_api.model.mole"]
+
+
+class TestMole(unittest.TestCase):
+    """Triangle unit test stubs"""
+
+    def setUp(self):
+        pass
+
+    def tearDown(self):
+        pass
+
+    def testMole(self):
+        # includes required parameters that are `readOnly=False` and not defined `readOnly`
+        my_mole = mole.Mole(smell="dirt", hearing=False)
+        assert my_mole.smell == "dirt"
+        assert my_mole.hearing is False
+
+        # includes required parameters that `readOnly=False`, an optional `readOnly=False` and not defined `readOnly`
+        my_mole = mole.Mole(smell="dirt", taste="kfc", hearing=True)
+        assert my_mole.smell == "dirt"
+        assert my_mole.taste == "kfc"
+        assert my_mole.hearing is True
+
+        # includes required parameters that `readOnly=False`, and required not defined `readOnly`, and an optional not defined
+        my_mole = mole.Mole(smell="dirt", seeing_ghosts=True, hearing=False)
+        assert my_mole.smell == "dirt"
+        assert my_mole.seeing_ghosts is True
+        assert my_mole.hearing is False
+
+        # passing in required readOnly parameters raises an exception
+        with self.assertRaises(ApiAttributeError):
+            mole.Mole(smell="dirt", hearing=False, blind=True)
+
+        # passing in optional readOnly parameters raises an exception
+        with self.assertRaises(ApiAttributeError):
+            mole.Mole(smell="dirt", hearing=False, touch=True)
+
+        # passing in required an optional parameters with readOnly true or false works with from_openapi_data
+        my_mole = mole.Mole._from_openapi_data(
+            smell="dirt",
+            taste="kfc",
+            blind=True,
+            touch=False,
+            hearing=True,
+            seeing_ghosts=False,
+        )
+        assert my_mole.smell == "dirt"
+        assert my_mole.taste == "kfc"
+        assert my_mole.blind is True
+        assert my_mole.touch is False
+        assert my_mole.hearing is True
+        assert my_mole.seeing_ghosts is False
+
+
+if __name__ == "__main__":
+    unittest.main()