Fix python-fastapi free-form objects mapping and forward ref type hints (#9723)

* map free-form objects to Dict[str, Any]

* support Forward Type References

Forward type references will be supported by default from Python 3.10 on only. Until then (and starting with Python 3.7), we can opt in by a __future__ import, cf. https://docs.python.org/3.9/whatsnew/3.7.html?highlight=forward#pep-563-postponed-evaluation-of-annotations

* re-created pet-store sample

* bump required Python version to 3.7 for generated FastAPI projects

* make pydantic modell classes process forward type references

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

@@ -1,9 +1,10 @@
 # coding: utf-8
 
+from __future__ import annotations
 from datetime import date, datetime  # noqa: F401
 
 import re  # noqa: F401
-from typing import Dict, List, Optional  # noqa: F401
+from typing import Any, Dict, List, Optional  # noqa: F401
 
 from pydantic import AnyUrl, BaseModel, EmailStr, validator  # noqa: F401
 
@@ -23,3 +24,5 @@ class ApiResponse(BaseModel):
     code: Optional[int] = None
     type: Optional[str] = None
     message: Optional[str] = None
+
+ApiResponse.update_forward_refs()

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

@@ -1,9 +1,10 @@
 # coding: utf-8
 
+from __future__ import annotations
 from datetime import date, datetime  # noqa: F401
 
 import re  # noqa: F401
-from typing import Dict, List, Optional  # noqa: F401
+from typing import Any, Dict, List, Optional  # noqa: F401
 
 from pydantic import AnyUrl, BaseModel, EmailStr, validator  # noqa: F401
 
@@ -26,3 +27,5 @@ class Category(BaseModel):
     def name_pattern(cls, value):
         assert value is not None and re.match(r"^[a-zA-Z0-9]+[a-zA-Z0-9\.\-_]*[a-zA-Z0-9]+$", value)
         return value
+
+Category.update_forward_refs()

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

@@ -1,9 +1,10 @@
 # coding: utf-8
 
+from __future__ import annotations
 from datetime import date, datetime  # noqa: F401
 
 import re  # noqa: F401
-from typing import Dict, List, Optional  # noqa: F401
+from typing import Any, Dict, List, Optional  # noqa: F401
 
 from pydantic import AnyUrl, BaseModel, EmailStr, validator  # noqa: F401
 
@@ -29,3 +30,5 @@ class Order(BaseModel):
     ship_date: Optional[datetime] = None
     status: Optional[str] = None
     complete: Optional[bool] = None
+
+Order.update_forward_refs()

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

@@ -1,9 +1,10 @@
 # coding: utf-8
 
+from __future__ import annotations
 from datetime import date, datetime  # noqa: F401
 
 import re  # noqa: F401
-from typing import Dict, List, Optional  # noqa: F401
+from typing import Any, Dict, List, Optional  # noqa: F401
 
 from pydantic import AnyUrl, BaseModel, EmailStr, validator  # noqa: F401
 from openapi_server.models.category import Category
@@ -31,3 +32,5 @@ class Pet(BaseModel):
     photo_urls: List[str]
     tags: Optional[List[Tag]] = None
     status: Optional[str] = None
+
+Pet.update_forward_refs()

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

@@ -1,9 +1,10 @@
 # coding: utf-8
 
+from __future__ import annotations
 from datetime import date, datetime  # noqa: F401
 
 import re  # noqa: F401
-from typing import Dict, List, Optional  # noqa: F401
+from typing import Any, Dict, List, Optional  # noqa: F401
 
 from pydantic import AnyUrl, BaseModel, EmailStr, validator  # noqa: F401
 
@@ -21,3 +22,5 @@ class Tag(BaseModel):
 
     id: Optional[int] = None
     name: Optional[str] = None
+
+Tag.update_forward_refs()

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

@@ -1,9 +1,10 @@
 # coding: utf-8
 
+from __future__ import annotations
 from datetime import date, datetime  # noqa: F401
 
 import re  # noqa: F401
-from typing import Dict, List, Optional  # noqa: F401
+from typing import Any, Dict, List, Optional  # noqa: F401
 
 from pydantic import AnyUrl, BaseModel, EmailStr, validator  # noqa: F401
 
@@ -33,3 +34,5 @@ class User(BaseModel):
     password: Optional[str] = None
     phone: Optional[str] = None
     user_status: Optional[int] = None
+
+User.update_forward_refs()