Route params (query or post) with future annotations gives "not fully defined" error

[ashb]

Minimal repro example:

from __future__ import annotations

from pydantic import BaseModel

from cadwyn import Cadwyn, Version, VersionBundle, VersionedAPIRouter


class MyModel(BaseModel):
    hello: str


router = VersionedAPIRouter()


@router.get("/")
async def root(input: MyModel):
    return {"hello": input.hello}


app = Cadwyn(versions=VersionBundle(Version("2000-01-01")))
app.generate_and_include_versioned_routers(router)

If you run this app and navigate to the docs page (http://127.0.0.1:8000/docs?version=2000-01-01) you get an error:

...
  File "/Users/ash/code/airflow/cadwyn-tmp/.venv/lib/python3.12/site-packages/starlette/routing.py", line 73, in app
    response = await f(request)
               ^^^^^^^^^^^^^^^^
  File "/Users/ash/code/airflow/cadwyn-tmp/.venv/lib/python3.12/site-packages/cadwyn/applications.py", line 303, in openapi_jsons
    get_openapi(
  File "/Users/ash/code/airflow/cadwyn-tmp/.venv/lib/python3.12/site-packages/fastapi/openapi/utils.py", line 493, in get_openapi
    field_mapping, definitions = get_definitions(
                                 ^^^^^^^^^^^^^^^^
  File "/Users/ash/code/airflow/cadwyn-tmp/.venv/lib/python3.12/site-packages/fastapi/_compat.py", line 231, in get_definitions
    field_mapping, definitions = schema_generator.generate_definitions(
                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/ash/code/airflow/cadwyn-tmp/.venv/lib/python3.12/site-packages/pydantic/json_schema.py", line 361, in generate_definitions
    self.generate_inner(schema)
  File "/Users/ash/code/airflow/cadwyn-tmp/.venv/lib/python3.12/site-packages/pydantic/json_schema.py", line 441, in generate_inner
    if 'ref' in schema:
       ^^^^^^^^^^^^^^^
  File "<frozen _collections_abc>", line 813, in __contains__
  File "/Users/ash/code/airflow/cadwyn-tmp/.venv/lib/python3.12/site-packages/pydantic/_internal/_mock_val_ser.py", line 41, in __getitem__
    return self._get_built().__getitem__(key)
           ^^^^^^^^^^^^^^^^^
  File "/Users/ash/code/airflow/cadwyn-tmp/.venv/lib/python3.12/site-packages/pydantic/_internal/_mock_val_ser.py", line 58, in _get_built
    raise PydanticUserError(self._error_message, code=self._code)
pydantic.errors.PydanticUserError: `TypeAdapter[typing.Annotated[ForwardRef('MyModel'), Query(PydanticUndefined)]]` is not fully defined; you should define `typing.Annotated[ForwardRef('MyModel'), Query(PydanticUndefined)]` and all referenced types, then call `.rebuild()` on
 the instance.

Removing the future import on line 1 gets rid of the problem.

This only applies if the MyModel is used as an input param to the function, it works fine with future annotations for return values.

[ashb]

Apache Airflow has a coding style that every file must have from __future__ import annotations which is how I discovered this

[zmievsa]

Thanks for reporting and thanks for a clear example! I'll get to this immediately.

[zmievsa]

This is a tougher problem than I expected. I found the solution for your case but it will require all forwardrefs within route dependencies to be fully resolvable at the point of app startup (i.e. the beginning of app's lifetime, i.e. on_startup event).

I would assume that they will be so it probably shouldn't be a problem. I'll publish and explain the solution once I'm able to implement it: hopefully within the next 3-4 days.

[zmievsa]

@ashb I fixed the routes issue but I found another issue while testing: if you use from __future__ import annotations in your schema definitions as well and you have many nested schemas, then cadwyn will also not work super well.

Will fix it as a part of PR opened above this week.