Manually Specifying a ForeignKey breaks fastapi

[gazpachoking]

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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

[YuriiMotov]

Works fine in current version (0.0.24):

CREATE TABLE team ( id INTEGER NOT NULL, PRIMARY KEY (id) ) CREATE TABLE hero ( id INTEGER NOT NULL, team_id INTEGER NOT NULL, PRIMARY KEY (id), FOREIGN KEY(team_id) REFERENCES team (id) )