Fix issue with fastapi generator converting all fields to snake_case (#12261)

* Fix issue with python-fastapi generator converting all fields to snake_case

* Update Python-FastAPI sample

Co-authored-by: Rory Dungan <contact@rorydungan.com>

modules/openapi-generator/src/main/resources/python-fastapi/api.mustache

@@ -41,6 +41,7 @@ router = APIRouter()
     {{#description}}
     description = "{{.}}",
     {{/description}}
+    response_model_by_alias=True,
 )
 async def {{operationId}}(
     {{#allParams}}

modules/openapi-generator/src/main/resources/python-fastapi/model.mustache

@@ -6,7 +6,7 @@ from datetime import date, datetime  # noqa: F401
 import re  # noqa: F401
 from typing import Any, Dict, List, Optional  # noqa: F401
 
-from pydantic import AnyUrl, BaseModel, EmailStr, validator  # noqa: F401
+from pydantic import AnyUrl, BaseModel, EmailStr, Field, validator  # noqa: F401
 {{#models}}
 {{#model}}
 {{#pyImports}}
@@ -31,7 +31,7 @@ class {{classname}}(BaseModel):
     """
 
 {{#vars}}
-    {{name}}: {{#required}}{{>model_field_type}}{{/required}}{{^required}}Optional[{{>model_field_type}}] = None{{/required}}
+    {{name}}: {{#required}}{{>model_field_type}}{{/required}}{{^required}}Optional[{{>model_field_type}}]{{/required}} = Field(alias="{{baseName}}"{{^required}}, default=None{{/required}})
 {{/vars}}
 {{#vars}}
 {{#maximum}}

samples/server/petstore/python-fastapi/src/openapi_server/apis/pet_api.py

@@ -32,6 +32,7 @@ router = APIRouter()
     },
     tags=["pet"],
     summary="Add a new pet to the store",
+    response_model_by_alias=True,
 )
 async def add_pet(
     pet: Pet = Body(None, description="Pet object that needs to be added to the store"),
@@ -50,6 +51,7 @@ async def add_pet(
     },
     tags=["pet"],
     summary="Deletes a pet",
+    response_model_by_alias=True,
 )
 async def delete_pet(
     petId: int = Path(None, description="Pet id to delete"),
@@ -70,6 +72,7 @@ async def delete_pet(
     },
     tags=["pet"],
     summary="Finds Pets by status",
+    response_model_by_alias=True,
 )
 async def find_pets_by_status(
     status: List[str] = Query(None, description="Status values that need to be considered for filter"),
@@ -89,6 +92,7 @@ async def find_pets_by_status(
     },
     tags=["pet"],
     summary="Finds Pets by tags",
+    response_model_by_alias=True,
 )
 async def find_pets_by_tags(
     tags: List[str] = Query(None, description="Tags to filter by"),
@@ -109,6 +113,7 @@ async def find_pets_by_tags(
     },
     tags=["pet"],
     summary="Find pet by ID",
+    response_model_by_alias=True,
 )
 async def get_pet_by_id(
     petId: int = Path(None, description="ID of pet to return"),
@@ -130,6 +135,7 @@ async def get_pet_by_id(
     },
     tags=["pet"],
     summary="Update an existing pet",
+    response_model_by_alias=True,
 )
 async def update_pet(
     pet: Pet = Body(None, description="Pet object that needs to be added to the store"),
@@ -148,6 +154,7 @@ async def update_pet(
     },
     tags=["pet"],
     summary="Updates a pet in the store with form data",
+    response_model_by_alias=True,
 )
 async def update_pet_with_form(
     petId: int = Path(None, description="ID of pet that needs to be updated"),
@@ -168,6 +175,7 @@ async def update_pet_with_form(
     },
     tags=["pet"],
     summary="uploads an image",
+    response_model_by_alias=True,
 )
 async def upload_file(
     petId: int = Path(None, description="ID of pet to update"),

samples/server/petstore/python-fastapi/src/openapi_server/apis/store_api.py

@@ -31,6 +31,7 @@ router = APIRouter()
     },
     tags=["store"],
     summary="Delete purchase order by ID",
+    response_model_by_alias=True,
 )
 async def delete_order(
     orderId: str = Path(None, description="ID of the order that needs to be deleted"),
@@ -46,6 +47,7 @@ async def delete_order(
     },
     tags=["store"],
     summary="Returns pet inventories by status",
+    response_model_by_alias=True,
 )
 async def get_inventory(
     token_api_key: TokenModel = Security(
@@ -65,6 +67,7 @@ async def get_inventory(
     },
     tags=["store"],
     summary="Find purchase order by ID",
+    response_model_by_alias=True,
 )
 async def get_order_by_id(
     orderId: int = Path(None, description="ID of pet that needs to be fetched", ge=1, le=5),
@@ -81,6 +84,7 @@ async def get_order_by_id(
     },
     tags=["store"],
     summary="Place an order for a pet",
+    response_model_by_alias=True,
 )
 async def place_order(
     order: Order = Body(None, description="order placed for purchasing the pet"),

samples/server/petstore/python-fastapi/src/openapi_server/apis/user_api.py

@@ -30,6 +30,7 @@ router = APIRouter()
     },
     tags=["user"],
     summary="Create user",
+    response_model_by_alias=True,
 )
 async def create_user(
     user: User = Body(None, description="Created user object"),
@@ -48,6 +49,7 @@ async def create_user(
     },
     tags=["user"],
     summary="Creates list of users with given input array",
+    response_model_by_alias=True,
 )
 async def create_users_with_array_input(
     user: List[User] = Body(None, description="List of user object"),
@@ -66,6 +68,7 @@ async def create_users_with_array_input(
     },
     tags=["user"],
     summary="Creates list of users with given input array",
+    response_model_by_alias=True,
 )
 async def create_users_with_list_input(
     user: List[User] = Body(None, description="List of user object"),
@@ -85,6 +88,7 @@ async def create_users_with_list_input(
     },
     tags=["user"],
     summary="Delete user",
+    response_model_by_alias=True,
 )
 async def delete_user(
     username: str = Path(None, description="The name that needs to be deleted"),
@@ -105,6 +109,7 @@ async def delete_user(
     },
     tags=["user"],
     summary="Get user by user name",
+    response_model_by_alias=True,
 )
 async def get_user_by_name(
     username: str = Path(None, description="The name that needs to be fetched. Use user1 for testing."),
@@ -121,6 +126,7 @@ async def get_user_by_name(
     },
     tags=["user"],
     summary="Logs user into the system",
+    response_model_by_alias=True,
 )
 async def login_user(
     username: str = Query(None, description="The user name for login", regex=r"^[a-zA-Z0-9]+[a-zA-Z0-9\.\-_]*[a-zA-Z0-9]+$"),
@@ -137,6 +143,7 @@ async def login_user(
     },
     tags=["user"],
     summary="Logs out current logged in user session",
+    response_model_by_alias=True,
 )
 async def logout_user(
     token_api_key: TokenModel = Security(
@@ -155,6 +162,7 @@ async def logout_user(
     },
     tags=["user"],
     summary="Updated user",
+    response_model_by_alias=True,
 )
 async def update_user(
     username: str = Path(None, description="name that need to be deleted"),

samples/server/petstore/python-fastapi/src/openapi_server/models/api_response.py

@@ -6,7 +6,7 @@ from datetime import date, datetime  # noqa: F401
 import re  # noqa: F401
 from typing import Any, Dict, List, Optional  # noqa: F401
 
-from pydantic import AnyUrl, BaseModel, EmailStr, validator  # noqa: F401
+from pydantic import AnyUrl, BaseModel, EmailStr, Field, validator  # noqa: F401
 
 
 class ApiResponse(BaseModel):
@@ -21,8 +21,8 @@ class ApiResponse(BaseModel):
         message: The message of this ApiResponse [Optional].
     """
 
-    code: Optional[int] = None
-    type: Optional[str] = None
-    message: Optional[str] = None
+    code: Optional[int] = Field(alias="code", default=None)
+    type: Optional[str] = Field(alias="type", default=None)
+    message: Optional[str] = Field(alias="message", default=None)
 
 ApiResponse.update_forward_refs()

samples/server/petstore/python-fastapi/src/openapi_server/models/category.py

@@ -6,7 +6,7 @@ from datetime import date, datetime  # noqa: F401
 import re  # noqa: F401
 from typing import Any, Dict, List, Optional  # noqa: F401
 
-from pydantic import AnyUrl, BaseModel, EmailStr, validator  # noqa: F401
+from pydantic import AnyUrl, BaseModel, EmailStr, Field, validator  # noqa: F401
 
 
 class Category(BaseModel):
@@ -20,8 +20,8 @@ class Category(BaseModel):
         name: The name of this Category [Optional].
     """
 
-    id: Optional[int] = None
-    name: Optional[str] = None
+    id: Optional[int] = Field(alias="id", default=None)
+    name: Optional[str] = Field(alias="name", default=None)
 
     @validator("name")
     def name_pattern(cls, value):

samples/server/petstore/python-fastapi/src/openapi_server/models/order.py

@@ -6,7 +6,7 @@ from datetime import date, datetime  # noqa: F401
 import re  # noqa: F401
 from typing import Any, Dict, List, Optional  # noqa: F401
 
-from pydantic import AnyUrl, BaseModel, EmailStr, validator  # noqa: F401
+from pydantic import AnyUrl, BaseModel, EmailStr, Field, validator  # noqa: F401
 
 
 class Order(BaseModel):
@@ -24,11 +24,11 @@ class Order(BaseModel):
         complete: The complete of this Order [Optional].
     """
 
-    id: Optional[int] = None
-    pet_id: Optional[int] = None
-    quantity: Optional[int] = None
-    ship_date: Optional[datetime] = None
-    status: Optional[str] = None
-    complete: Optional[bool] = None
+    id: Optional[int] = Field(alias="id", default=None)
+    pet_id: Optional[int] = Field(alias="petId", default=None)
+    quantity: Optional[int] = Field(alias="quantity", default=None)
+    ship_date: Optional[datetime] = Field(alias="shipDate", default=None)
+    status: Optional[str] = Field(alias="status", default=None)
+    complete: Optional[bool] = Field(alias="complete", default=None)
 
 Order.update_forward_refs()

samples/server/petstore/python-fastapi/src/openapi_server/models/pet.py

@@ -6,7 +6,7 @@ from datetime import date, datetime  # noqa: F401
 import re  # noqa: F401
 from typing import Any, Dict, List, Optional  # noqa: F401
 
-from pydantic import AnyUrl, BaseModel, EmailStr, validator  # noqa: F401
+from pydantic import AnyUrl, BaseModel, EmailStr, Field, validator  # noqa: F401
 from openapi_server.models.category import Category
 from openapi_server.models.tag import Tag
 
@@ -26,11 +26,11 @@ class Pet(BaseModel):
         status: The status of this Pet [Optional].
     """
 
-    id: Optional[int] = None
-    category: Optional[Category] = None
-    name: str
-    photo_urls: List[str]
-    tags: Optional[List[Tag]] = None
-    status: Optional[str] = None
+    id: Optional[int] = Field(alias="id", default=None)
+    category: Optional[Category] = Field(alias="category", default=None)
+    name: str = Field(alias="name")
+    photo_urls: List[str] = Field(alias="photoUrls")
+    tags: Optional[List[Tag]] = Field(alias="tags", default=None)
+    status: Optional[str] = Field(alias="status", default=None)
 
 Pet.update_forward_refs()

samples/server/petstore/python-fastapi/src/openapi_server/models/tag.py

@@ -6,7 +6,7 @@ from datetime import date, datetime  # noqa: F401
 import re  # noqa: F401
 from typing import Any, Dict, List, Optional  # noqa: F401
 
-from pydantic import AnyUrl, BaseModel, EmailStr, validator  # noqa: F401
+from pydantic import AnyUrl, BaseModel, EmailStr, Field, validator  # noqa: F401
 
 
 class Tag(BaseModel):
@@ -20,7 +20,7 @@ class Tag(BaseModel):
         name: The name of this Tag [Optional].
     """
 
-    id: Optional[int] = None
-    name: Optional[str] = None
+    id: Optional[int] = Field(alias="id", default=None)
+    name: Optional[str] = Field(alias="name", default=None)
 
 Tag.update_forward_refs()

samples/server/petstore/python-fastapi/src/openapi_server/models/user.py

@@ -6,7 +6,7 @@ from datetime import date, datetime  # noqa: F401
 import re  # noqa: F401
 from typing import Any, Dict, List, Optional  # noqa: F401
 
-from pydantic import AnyUrl, BaseModel, EmailStr, validator  # noqa: F401
+from pydantic import AnyUrl, BaseModel, EmailStr, Field, validator  # noqa: F401
 
 
 class User(BaseModel):
@@ -26,13 +26,13 @@ class User(BaseModel):
         user_status: The user_status of this User [Optional].
     """
 
-    id: Optional[int] = None
-    username: Optional[str] = None
-    first_name: Optional[str] = None
-    last_name: Optional[str] = None
-    email: Optional[str] = None
-    password: Optional[str] = None
-    phone: Optional[str] = None
-    user_status: Optional[int] = None
+    id: Optional[int] = Field(alias="id", default=None)
+    username: Optional[str] = Field(alias="username", default=None)
+    first_name: Optional[str] = Field(alias="firstName", default=None)
+    last_name: Optional[str] = Field(alias="lastName", default=None)
+    email: Optional[str] = Field(alias="email", default=None)
+    password: Optional[str] = Field(alias="password", default=None)
+    phone: Optional[str] = Field(alias="phone", default=None)
+    user_status: Optional[int] = Field(alias="userStatus", default=None)
 
 User.update_forward_refs()