[python-server] Support python 3.7 for all server-generators (#2884)

* Support python 3.7 for all server-generators

Signed-off-by: Guillaume Smaha <guillaume.smaha@gmail.com>

* Rename typing_patch.py to typing_utils.py

* Renaming typing_patch.mustache to typing_utils.mustache

* Fix comparaison in typing_utils.is_dict for python3.7

samples/server/petstore/python-flask/.openapi-generator/VERSION

@@ -1 +1 @@
-4.0.0-SNAPSHOT
+4.0.0

samples/server/petstore/python-flask/openapi_server/openapi/openapi.yaml

@@ -1,6 +1,7 @@
 openapi: 3.0.1
 info:
-  description: This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+  description: This is a sample server Petstore server. For this sample, you can use
+    the api key `special-key` to test the authorization filters.
   license:
     name: Apache-2.0
     url: http://www.apache.org/licenses/LICENSE-2.0.html
@@ -121,7 +122,8 @@ paths:
   /pet/findByTags:
     get:
       deprecated: true
-      description: Multiple tags can be provided with comma separated strings. Use tag1, tag2, tag3 for testing.
+      description: Multiple tags can be provided with comma separated strings. Use
+        tag1, tag2, tag3 for testing.
       operationId: find_pets_by_tags
       parameters:
       - description: Tags to filter by
@@ -340,7 +342,8 @@ paths:
       x-openapi-router-controller: openapi_server.controllers.store_controller
   /store/order/{orderId}:
     delete:
-      description: For valid response try integer IDs with value < 1000. Anything above 1000 or nonintegers will generate API errors
+      description: For valid response try integer IDs with value < 1000. Anything
+        above 1000 or nonintegers will generate API errors
       operationId: delete_order
       parameters:
       - description: ID of the order that needs to be deleted
@@ -361,7 +364,8 @@ paths:
       - store
       x-openapi-router-controller: openapi_server.controllers.store_controller
     get:
-      description: For valid response try integer IDs with value <= 5 or > 10. Other values will generated exceptions
+      description: For valid response try integer IDs with value <= 5 or > 10. Other
+        values will generated exceptions
       operationId: get_order_by_id
       parameters:
       - description: ID of pet that needs to be fetched

samples/server/petstore/python-flask/openapi_server/typing_utils.py

@@ -0,0 +1,32 @@
+# coding: utf-8
+
+import sys
+
+if sys.version_info < (3, 7):
+    import typing
+
+    def is_generic(klass):
+        """ Determine whether klass is a generic class """
+        return type(klass) == typing.GenericMeta
+
+    def is_dict(klass):
+        """ Determine whether klass is a Dict """
+        return klass.__extra__ == dict
+
+    def is_list(klass):
+        """ Determine whether klass is a List """
+        return klass.__extra__ == list
+
+else:
+
+    def is_generic(klass):
+        """ Determine whether klass is a generic class """
+        return hasattr(klass, '__origin__')
+
+    def is_dict(klass):
+        """ Determine whether klass is a Dict """
+        return klass.__origin__ == dict
+
+    def is_list(klass):
+        """ Determine whether klass is a List """
+        return klass.__origin__ == list

samples/server/petstore/python-flask/openapi_server/util.py

@@ -2,6 +2,7 @@ import datetime
 
 import six
 import typing
+from openapi_server import typing_utils
 
 
 def _deserialize(data, klass):
@@ -23,10 +24,10 @@ def _deserialize(data, klass):
         return deserialize_date(data)
     elif klass == datetime.datetime:
         return deserialize_datetime(data)
-    elif type(klass) == typing.GenericMeta:
-        if klass.__extra__ == list:
+    elif typing_utils.is_generic(klass):
+        if typing_utils.is_list(klass):
             return _deserialize_list(data, klass.__args__[0])
-        if klass.__extra__ == dict:
+        if typing_utils.is_dict(klass):
             return _deserialize_dict(data, klass.__args__[1])
     else:
         return deserialize_model(data, klass)