Splitting sqlmodel example code in multiple files results in PydanticUserError

[fkarg]

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Example Code

(the only effective change I did seems to be changing the type signature of the fields in TeamPublicWithHeroes and HeroPublicWithTeam from direct to the indirect python "string" types, in both models.py files. It worked fine before I split it up, or when commenting out or changing the type of the stringified field types.)

Splitting up the example code from https://sqlmodel.tiangolo.com/tutorial/fastapi/relationships/ to multiple files, i.e. in the following way:

# heroes/models.py
from typing import TYPE_CHECKING
from sqlmodel import Field, Relationship, SQLModel

if TYPE_CHECKING:
    from teams.models import Team, TeamPublic

class HeroBase(SQLModel):
    name: str = Field(index=True)
    secret_name: str
    age: int | None = Field(default=None, index=True)
    team_id: int | None = Field(default=None, foreign_key="team.id")


class Hero(HeroBase, table=True):
    id: int | None = Field(default=None, primary_key=True)
    team: "Team | None" = Relationship(back_populates="heroes")


class HeroPublic(HeroBase):
    id: int


class HeroCreate(HeroBase):
    pass


class HeroUpdate(SQLModel):
    name: str | None = None
    secret_name: str | None = None
    age: int | None = None
    team_id: int | None = None


class HeroPublicWithTeam(HeroPublic):
    team: "TeamPublic | None" = None

# heroes/views.py
from fastapi import APIRouter, Depends, HTTPException, Query
from sqlalchemy.ext.asyncio import AsyncSession
from sqlmodel import select

from databases import get_session
from heroes.models import (
    Hero,
    HeroCreate,
    HeroPublic,
    HeroPublicWithTeam,
    HeroUpdate,
)

router = APIRouter()


@router.post("/heroes/", response_model=HeroPublic)
async def create_hero(
    *, session: AsyncSession = Depends(get_session), hero: HeroCreate
):
    db_hero = Hero.model_validate(hero)
    session.add(db_hero)
    await session.commit()
    await session.refresh(db_hero)
    return db_hero


@router.get("/heroes/", response_model=list[HeroPublic])
async def read_heroes(
    *,
    session: AsyncSession = Depends(get_session),
    offset: int = 0,
    limit: int = Query(default=100, le=100),
):
    heroes = await session.execute(select(Hero).offset(offset).limit(limit))
    return heroes.all()


@router.get("/heroes/{hero_id}", response_model=HeroPublicWithTeam)
async def read_hero(*, session: AsyncSession = Depends(get_session), hero_id: int):
    hero = await session.get(Hero, hero_id)
    if not hero:
        raise HTTPException(status_code=404, detail="Hero not found")
    return hero


@router.patch("/heroes/{hero_id}", response_model=HeroPublic)
async def update_hero(
    *, session: AsyncSession = Depends(get_session), hero_id: int, hero: HeroUpdate
):
    db_hero = await session.get(Hero, hero_id)
    if not db_hero:
        raise HTTPException(status_code=404, detail="Hero not found")
    hero_data = hero.model_dump(exclude_unset=True)
    for key, value in hero_data.items():
        setattr(db_hero, key, value)
    session.add(db_hero)
    await session.commit()
    await session.refresh(db_hero)
    return db_hero


@router.delete("/heroes/{hero_id}")
async def delete_hero(*, session: AsyncSession = Depends(get_session), hero_id: int):
    hero = await session.get(Hero, hero_id)
    if not hero:
        raise HTTPException(status_code=404, detail="Hero not found")
    await session.delete(hero)
    await session.commit()
    return {"ok": True}

# teams/models.py
from typing import List, TYPE_CHECKING
from sqlmodel import Field, Relationship, SQLModel

if TYPE_CHECKING:
    from heroes.models import Hero, HeroPublic

class TeamBase(SQLModel):
    name: str = Field(index=True)
    headquarters: str


class Team(TeamBase, table=True):
    id: int | None = Field(default=None, primary_key=True)
    heroes: List["Hero"] = Relationship(back_populates="team")


class TeamCreate(TeamBase):
    pass


class TeamPublic(TeamBase):
    id: int


class TeamUpdate(SQLModel):
    id: int | None = None
    name: str | None = None
    headquarters: str | None = None


class TeamPublicWithHeroes(TeamPublic):
    heroes: List["HeroPublic"] = []

# teams/views.py
from fastapi import APIRouter, Depends, HTTPException, Query
from sqlalchemy.ext.asyncio import AsyncSession
from sqlmodel import select

from databases import get_session
from teams.models import (
    Team,
    TeamCreate,
    TeamPublic,
    TeamPublicWithHeroes,
    TeamUpdate,
)

router = APIRouter()


@router.post("/teams/", response_model=TeamPublic)
async def create_team(
    *, session: AsyncSession = Depends(get_session), team: TeamCreate
):
    db_team = Team.model_validate(team)
    session.add(db_team)
    await session.commit()
    await session.refresh(db_team)
    return db_team


@router.get("/teams/", response_model=list[TeamPublic])
async def read_teams(
    *,
    session: AsyncSession = Depends(get_session),
    offset: int = 0,
    limit: int = Query(default=100, le=100),
):
    teams = await session.execute(select(Team).offset(offset).limit(limit))
    return teams.all()


@router.get("/teams/{team_id}", response_model=TeamPublicWithHeroes)
async def read_team(*, team_id: int, session: AsyncSession = Depends(get_session)):
    team = await session.get(Team, team_id)
    if not team:
        raise HTTPException(status_code=404, detail="Team not found")
    return team


@router.patch("/teams/{team_id}", response_model=TeamPublic)
async def update_team(
    *,
    session: AsyncSession = Depends(get_session),
    team_id: int,
    team: TeamUpdate,
):
    db_team = await session.get(Team, team_id)
    if not db_team:
        raise HTTPException(status_code=404, detail="Team not found")
    team_data = team.model_dump(exclude_unset=True)
    for key, value in team_data.items():
        setattr(db_team, key, value)
    session.add(db_team)
    await session.commit()
    await session.refresh(db_team)
    return db_team


@router.delete("/teams/{team_id}")
async def delete_team(*, session: AsyncSession = Depends(get_session), team_id: int):
    team = await session.get(Team, team_id)
    if not team:
        raise HTTPException(status_code=404, detail="Team not found")
    await session.delete(team)
    await session.commit()
    return {"ok": True}

# databases.py
from sqlalchemy.ext.asyncio import create_async_engine, async_sessionmaker
from sqlmodel.ext.asyncio.session import AsyncSession

from src.config import settings

engine = create_async_engine(settings.DATABASE_URL, echo=settings.DB_ECHO)


async def get_session():
    async_session = async_sessionmaker(engine, class_=AsyncSession, expire_on_commit=False)
    async with async_session() as session:
        yield session

# main.py
from fastapi import FastAPI

from heroes.views import router as heroes_router
from teams.views import router as teams_router
from databases import run_migrations

app = FastAPI(
    title="Debug API",
    description="Minimal API for debugging heroes and teams",
    version="0.1.0",
)

# Include only heroes and teams routers
app.include_router(heroes_router, tags=["Heroes"])
app.include_router(teams_router, tags=["Teams"])

if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="127.0.0.1", port=8000)

Description

Will result in the following error when attempting to view the swagger spec:

INFO:     127.0.0.1:43332 - "GET /api/docs HTTP/1.1" 200 OK
INFO:     127.0.0.1:43332 - "GET /api/openapi.json HTTP/1.1" 500 Internal Server Error
ERROR:    Exception in ASGI application
Traceback (most recent call last):
  File ".../.venv/lib/python3.12/site-packages/uvicorn/protocols/http/httptools_impl.py", line 409, in run_asgi
    result = await app(  # type: ignore[func-returns-value]
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ".../.venv/lib/python3.12/site-packages/uvicorn/middleware/proxy_headers.py", line 60, in __call__
    return await self.app(scope, receive, send)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ".../.venv/lib/python3.12/site-packages/fastapi/applications.py", line 1054, in __call__
    await super().__call__(scope, receive, send)
  File ".../.venv/lib/python3.12/site-packages/starlette/applications.py", line 113, in __call__
    await self.middleware_stack(scope, receive, send)
  File ".../.venv/lib/python3.12/site-packages/starlette/middleware/errors.py", line 187, in __call__
    raise exc
  File ".../.venv/lib/python3.12/site-packages/starlette/middleware/errors.py", line 165, in __call__
    await self.app(scope, receive, _send)
  File ".../.venv/lib/python3.12/site-packages/starlette/middleware/exceptions.py", line 62, in __call__
    await wrap_app_handling_exceptions(self.app, conn)(scope, receive, send)
  File ".../.venv/lib/python3.12/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app
    raise exc
  File ".../.venv/lib/python3.12/site-packages/starlette/_exception_handler.py", line 42, in wrapped_app
    await app(scope, receive, sender)
  File ".../.venv/lib/python3.12/site-packages/starlette/routing.py", line 715, in __call__
    await self.middleware_stack(scope, receive, send)
  File ".../.venv/lib/python3.12/site-packages/starlette/routing.py", line 735, in app
    await route.handle(scope, receive, send)
  File ".../.venv/lib/python3.12/site-packages/starlette/routing.py", line 460, in handle
    await self.app(scope, receive, send)
  File ".../.venv/lib/python3.12/site-packages/fastapi/applications.py", line 1054, in __call__
    await super().__call__(scope, receive, send)
  File ".../.venv/lib/python3.12/site-packages/starlette/applications.py", line 113, in __call__
    await self.middleware_stack(scope, receive, send)
  File ".../.venv/lib/python3.12/site-packages/starlette/middleware/errors.py", line 187, in __call__
    raise exc
  File ".../.venv/lib/python3.12/site-packages/starlette/middleware/errors.py", line 165, in __call__
    await self.app(scope, receive, _send)
  File ".../.venv/lib/python3.12/site-packages/starlette/middleware/exceptions.py", line 62, in __call__
    await wrap_app_handling_exceptions(self.app, conn)(scope, receive, send)
  File ".../.venv/lib/python3.12/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app
    raise exc
  File ".../.venv/lib/python3.12/site-packages/starlette/_exception_handler.py", line 42, in wrapped_app
    await app(scope, receive, sender)
  File ".../.venv/lib/python3.12/site-packages/starlette/routing.py", line 715, in __call__
    await self.middleware_stack(scope, receive, send)
  File ".../.venv/lib/python3.12/site-packages/starlette/routing.py", line 735, in app
    await route.handle(scope, receive, send)
  File ".../.venv/lib/python3.12/site-packages/starlette/routing.py", line 288, in handle
    await self.app(scope, receive, send)
  File ".../.venv/lib/python3.12/site-packages/starlette/routing.py", line 76, in app
    await wrap_app_handling_exceptions(app, request)(scope, receive, send)
  File ".../.venv/lib/python3.12/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app
    raise exc
  File ".../.venv/lib/python3.12/site-packages/starlette/_exception_handler.py", line 42, in wrapped_app
    await app(scope, receive, sender)
  File ".../.venv/lib/python3.12/site-packages/starlette/routing.py", line 73, in app
    response = await f(request)
               ^^^^^^^^^^^^^^^^
  File ".../.venv/lib/python3.12/site-packages/fastapi/applications.py", line 1009, in openapi
    return JSONResponse(self.openapi())
                        ^^^^^^^^^^^^^^
  File ".../.venv/lib/python3.12/site-packages/fastapi/applications.py", line 981, in openapi
    self.openapi_schema = get_openapi(
                          ^^^^^^^^^^^^
  File ".../.venv/lib/python3.12/site-packages/fastapi/openapi/utils.py", line 493, in get_openapi
    field_mapping, definitions = get_definitions(
                                 ^^^^^^^^^^^^^^^^
  File ".../.venv/lib/python3.12/site-packages/fastapi/_compat.py", line 231, in get_definitions
    field_mapping, definitions = schema_generator.generate_definitions(
                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ".../.venv/lib/python3.12/site-packages/pydantic/json_schema.py", line 361, in generate_definitions
    self.generate_inner(schema)
  File ".../.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 ".../.venv/lib/python3.12/site-packages/pydantic/_internal/_mock_val_ser.py", line 41, in __getitem__
    return self._get_built().__getitem__(key)
           ^^^^^^^^^^^^^^^^^
  File ".../.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[heroes.models.HeroPublicWithTeam, FieldInfo(annotation=HeroPublicWithTeam, required=True)]]` is not fully defined; you should define `typing.Annotated[heroes.models.HeroPublicWithTeam, FieldInfo(annotation=HeroPublicWithTeam, required=True)]` and all referenced types, then call `.rebuild()` on the instance.

which shows up as

in http://localhost:8000/api/docs#/

Operating System

Linux, Windows

Operating System Details

~> neofetch
          ▗▄▄▄       ▗▄▄▄▄    ▄▄▄▖            pars@margo 
          ▜███▙       ▜███▙  ▟███▛            ---------- 
           ▜███▙       ▜███▙▟███▛             OS: NixOS 25.05pre745949.9189ac18287c (Warbler) x86_64 
            ▜███▙       ▜██████▛              Host: Framework FRANMECP02 
     ▟█████████████████▙ ▜████▛     ▟▙        Kernel: 6.12.5 
    ▟███████████████████▙ ▜███▙    ▟██▙       Uptime: 41 days, 7 hours, 3 mins 
           ▄▄▄▄▖           ▜███▙  ▟███▛       Packages: 1732 (nix-system), 5302 (nix-user) 
          ▟███▛             ▜██▛ ▟███▛        Shell: fish 3.7.1 
         ▟███▛               ▜▛ ▟███▛         Resolution: 2256x1504, 1920x1080 
▟███████████▛                  ▟██████████▙   DE: none+i3 
▜██████████▛                  ▟███████████▛   WM: i3 
      ▟███▛ ▟▙               ▟███▛            Terminal: kitty 
     ▟███▛ ▟██▙             ▟███▛             Terminal Font: monospace 16.0 
    ▟███▛  ▜███▙           ▝▀▀▀▀              CPU: Intel Ultra 5 125H (18) @ 4.500GHz 
    ▜██▛    ▜███▙ ▜██████████████████▛        GPU: Intel Arc Graphics] 
     ▜▛     ▟████▙ ▜████████████████▛         Memory: 40429MiB / 47636MiB 
           ▟██████▙       ▜███▙
          ▟███▛▜███▙       ▜███▙                                      
         ▟███▛  ▜███▙       ▜███▙                                     
         ▝▀▀▀    ▀▀▀▀▘       ▀▀▀▘

Also tested on a Win11 machine with Ubuntu WSL with the same result.

SQLModel Version

0.0.22

Python Version

3.12.8

Additional Context

No response

[benoit-arcsec]

Adding relationship in the public interface seems to work:

...

class HeroPublicWithTeam(HeroPublic):
    team: "TeamPublic | None" = Relationship()

...

class TeamPublicWithHeroes(TeamPublic):
    heroes: List["HeroPublic"] = Relationship()

Side note: You do not need List, list is ok.

[dnszero]

Thank you so much for posting the fix! I've been hitting the same error for the last hour and this fixed it for me too.

[dnszero]

Actually, I spoke too soon. Adding in = Relationship() got rid of the errors, but now the relationship doesn't show up in Swagger schema.

[YuriiMotov]

You have circular references and to resolve it you need to rebuild your models.

Add the following to __init__.py:

from heroes.models import HeroPublicWithTeam, HeroPublic
from teams.models import TeamPublicWithHeroes, TeamPublic

HeroPublicWithTeam.model_rebuild()
TeamPublicWithHeroes.model_rebuild()

[ethan-cassel-mace]

HI @YuriiMotov - thanks for this solution. I have a mature app with probably ~100 models, many of which have circular references. I started hitting this issue after upgrading from pydantic 2.5, which i needed to do to solve dependency conflicts. Can you help me understand the generalized solution here? Should I basically call MyModel.model_rebuild() for every model in the app after all models have been imported?