Manually Specifying a ForeignKey breaks fastapi

[gazpachoking]

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• I already checked if it is not related to SQLModel but to SQLAlchemy.

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Example Code

import fastapi
import sqlmodel
import uvicorn
import sqlalchemy as sa


class Hero(sqlmodel.SQLModel, table=True):
    id: int = sqlmodel.Field(primary_key=True)
    # This one works fine
    #team_id: int = sqlmodel.Field(foreign_key="team.id")
    # This one breaks everything
    team_id: int = sqlmodel.Field(sa_column_args=[sa.ForeignKey('team.id')])


class Team(sqlmodel.SQLModel, table=True):
    id: int = sqlmodel.Field(primary_key=True)


engine = sqlmodel.create_engine('sqlite://')
sqlmodel.SQLModel.metadata.create_all(bind=engine)


app = fastapi.FastAPI()


@app.get('/', response_model=list[Hero])
async def get_heroes() -> list[Hero]:
    with sqlmodel.Session(engine) as session:
        return session.exec(sqlmodel.select(Hero)).all()


if __name__ == '__main__':
    with sqlmodel.Session(engine) as session:
        team = Team(id=1)
        session.add(team)
        session.add(Hero(team_id=team.id))
        session.commit()
    uvicorn.run(app, host='0.0.0.0', port=8888)

Description

I'm trying to add extra properties to the ForeignKey definition for my fields. (Specifically, deferrable and initially) To define those properties, I have to change to specify sa_column_args to define the ForeignKey manually. This works fine, until you try to use the model in a FastAPI application, at which point the app doesn't even start up.

Traceback (most recent call last):
  File "C:\Users\chase.sterling\PycharmProjects\testproject\testfile.py", line 27, in <module>
    async def get_heroes() -> list[Hero]:
  File "C:\Users\chase.sterling\PycharmProjects\testproject\.venv\lib\site-packages\fastapi\routing.py", line 921, in decorator
    self.add_api_route(
  File "C:\Users\chase.sterling\PycharmProjects\testproject\.venv\lib\site-packages\fastapi\routing.py", line 860, in add_api_route
    route = route_class(
  File "C:\Users\chase.sterling\PycharmProjects\testproject\.venv\lib\site-packages\fastapi\routing.py", line 464, in __init__
    ] = create_cloned_field(self.response_field)
  File "C:\Users\chase.sterling\PycharmProjects\testproject\.venv\lib\site-packages\fastapi\utils.py", line 132, in create_cloned_field
    use_type = create_model(original_type.__name__, __base__=original_type)
  File "pydantic\main.py", line 1026, in pydantic.main.create_model
  File "C:\Users\chase.sterling\PycharmProjects\testproject\.venv\lib\site-packages\sqlmodel\main.py", line 446, in __new__
    col = get_column_from_field(v)
  File "C:\Users\chase.sterling\PycharmProjects\testproject\.venv\lib\site-packages\sqlmodel\main.py", line 621, in get_column_from_field
    return Column(sa_type, *args, **kwargs)  # type: ignore
  File "C:\Users\chase.sterling\PycharmProjects\testproject\.venv\lib\site-packages\sqlalchemy\sql\schema.py", line 1767, in __init__
    self._init_items(*args)
  File "C:\Users\chase.sterling\PycharmProjects\testproject\.venv\lib\site-packages\sqlalchemy\sql\schema.py", line 144, in _init_items
    spwd(self, **kw)
  File "C:\Users\chase.sterling\PycharmProjects\testproject\.venv\lib\site-packages\sqlalchemy\sql\base.py", line 1047, in _set_parent_with_dispatch
    self._set_parent(parent, **kw)
  File "C:\Users\chase.sterling\PycharmProjects\testproject\.venv\lib\site-packages\sqlalchemy\sql\schema.py", line 2572, in _set_parent
    raise exc.InvalidRequestError(
sqlalchemy.exc.InvalidRequestError: This ForeignKey already has a parent !

It seems like FastAPI ends up affecting the sqlalchemy side of the model when it does the create_cloned_field rather than just the pydantic part.

Operating System

Windows

Operating System Details

No response

SQLModel Version

0.0.11

Python Version

3.10.11

Additional Context

fastapi 0.104.1