Reference to other models to get data in many-to-many relationships

[dongsupkim-onepredict]

First Check

• I added a very descriptive title here.
• I used the GitHub search to find a similar question and didn't find it.
• I searched the SQLModel documentation, with the integrated search.
• I already searched in Google "How to X in SQLModel" and didn't find any information.
• I already read and followed all the tutorial in the docs and didn't find an answer.
• I already checked if it is not related to SQLModel but to Pydantic.
• I already checked if it is not related to SQLModel but to SQLAlchemy.

Commit to Help

• I commit to help with one of those options 👆

Example Code

# Link Table for user and role
class UserRole(SQLModel, table=True):
    id: Optional[int] = Field(default=None, primary_key=True)
    user_id: Optional[int] = Field(foreign_key='user.id', default=None)
    role_id: Optional[int] = Field(foreign_key='role.id', default=None)
    created_at: datetime = Field(default=datetime.now(), nullable=False)
    updated_at: datetime = Field(sa_column=Column(DateTime, default=datetime.now(), onupdate=datetime.now(), nullable=False))
    
class UserBase(SQLModel):
    username: str = Field(index=True, nullable=False, unique=True)
    password: str = Field(nullable=False)
    email: str = Field(index=True, nullable=False, unique=True)
    full_name: str = Field(nullable=False)
    is_active: bool = Field(nullable=False)
    is_superuser: bool = Field(nullable=False)

class User(UserBase, table=True):
    id: Optional[int] = Field(default=None, primary_key=True)
    created_at: datetime = Field(default=datetime.now(), nullable=False)
    updated_at: datetime = Field(sa_column=Column(DateTime, default=datetime.now(), onupdate=datetime.now(), nullable=False))
    roles: List['Role'] = Relationship(back_populates='users', link_model=UserRole)

class UserRead(UserBase):
    id: int
    created_at: datetime
    updated_at: datetime

class UserReadWithRoles(UserRead):
    roles: List['RoleRead'] = []



class RoleBase(SQLModel):
    name: str = Field(max_length=30)
    description: Optional[str]  = Field(max_length=300)
    

class Role(RoleBase, table=True):
    id: Optional[int] = Field(default=None, primary_key=True)
    created_at: datetime = Field(default=datetime.now(), nullable=False)
    updated_at: datetime = Field(sa_column=Column(DateTime, 
                                                  default=datetime.now(), 
                                                  onupdate=datetime.now(), 
                                                  nullable=False))
    users: List['User'] = Relationship(back_populates='roles', link_model=UserRole)

class RoleRead(RoleBase):
    id: int
    created_at: datetime
    updated_at: datetime

class RoleReadWithUsers(RoleRead):
    users: Optional[List['UserRead']]



@router.get("/{username}", response_model=UserReadWithRoles)
async def read_user(username: str, session: Session = Depends(get_session)):
    user = get_user(session, username)
    return user

Description

I'd like to return UserReadWithRoles response model that includes user and role data in many to many relationships using link_model as you can see

It doesn't show up any error when run python script but when I try to access openapi docs it make error as below:

Traceback (most recent call last):
  File "/home/pdx/workspace/fastapi-admin/venv/lib/python3.9/site-packages/uvicorn/protocols/http/h11_impl.py", line 404, in run_asgi
    result = await app(  # type: ignore[func-returns-value]
  File "/home/pdx/workspace/fastapi-admin/venv/lib/python3.9/site-packages/uvicorn/middleware/proxy_headers.py", line 78, in __call__
    return await self.app(scope, receive, send)
  File "/home/pdx/workspace/fastapi-admin/venv/lib/python3.9/site-packages/fastapi/applications.py", line 270, in __call__
    await super().__call__(scope, receive, send)
  File "/home/pdx/workspace/fastapi-admin/venv/lib/python3.9/site-packages/starlette/applications.py", line 124, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/home/pdx/workspace/fastapi-admin/venv/lib/python3.9/site-packages/starlette/middleware/errors.py", line 184, in __call__
    raise exc
  File "/home/pdx/workspace/fastapi-admin/venv/lib/python3.9/site-packages/starlette/middleware/errors.py", line 162, in __call__
    await self.app(scope, receive, _send)
  File "/home/pdx/workspace/fastapi-admin/venv/lib/python3.9/site-packages/starlette/middleware/cors.py", line 84, in __call__
    await self.app(scope, receive, send)
  File "/home/pdx/workspace/fastapi-admin/venv/lib/python3.9/site-packages/starlette/middleware/exceptions.py", line 75, in __call__
    raise exc
  File "/home/pdx/workspace/fastapi-admin/venv/lib/python3.9/site-packages/starlette/middleware/exceptions.py", line 64, in __call__
    await self.app(scope, receive, sender)
  File "/home/pdx/workspace/fastapi-admin/venv/lib/python3.9/site-packages/fastapi/middleware/asyncexitstack.py", line 21, in __call__
    raise e
  File "/home/pdx/workspace/fastapi-admin/venv/lib/python3.9/site-packages/fastapi/middleware/asyncexitstack.py", line 18, in __call__
    await self.app(scope, receive, send)
  File "/home/pdx/workspace/fastapi-admin/venv/lib/python3.9/site-packages/starlette/routing.py", line 680, in __call__
    await route.handle(scope, receive, send)
  File "/home/pdx/workspace/fastapi-admin/venv/lib/python3.9/site-packages/starlette/routing.py", line 275, in handle
    await self.app(scope, receive, send)
  File "/home/pdx/workspace/fastapi-admin/venv/lib/python3.9/site-packages/starlette/routing.py", line 65, in app
    response = await func(request)
  File "/home/pdx/workspace/fastapi-admin/venv/lib/python3.9/site-packages/fastapi/applications.py", line 225, in openapi
    return JSONResponse(self.openapi())
  File "/home/pdx/workspace/fastapi-admin/venv/lib/python3.9/site-packages/fastapi/applications.py", line 200, in openapi
    self.openapi_schema = get_openapi(
  File "/home/pdx/workspace/fastapi-admin/venv/lib/python3.9/site-packages/fastapi/openapi/utils.py", line 423, in get_openapi
    definitions = get_model_definitions(
  File "/home/pdx/workspace/fastapi-admin/venv/lib/python3.9/site-packages/fastapi/utils.py", line 45, in get_model_definitions
    m_schema, m_definitions, m_nested_models = model_process_schema(
  File "pydantic/schema.py", line 582, in pydantic.schema.model_process_schema
  File "pydantic/schema.py", line 623, in pydantic.schema.model_type_schema
  File "pydantic/schema.py", line 256, in pydantic.schema.field_schema
  File "pydantic/schema.py", line 463, in pydantic.schema.field_type_schema
  File "pydantic/schema.py", line 853, in pydantic.schema.field_singleton_schema
  File "pydantic/schema.py", line 702, in pydantic.schema.field_singleton_sub_fields_schema
  File "pydantic/schema.py", line 528, in pydantic.schema.field_type_schema
  File "pydantic/schema.py", line 927, in pydantic.schema.field_singleton_schema
  File "/usr/lib/python3.9/abc.py", line 123, in __subclasscheck__
    return _abc_subclasscheck(cls, subclass)
TypeError: issubclass() arg 1 must be a class

But only thing that I can reference is this page reference

It only shows one-to-many relationships case. Is there any reference or any code?

Operating System

macOS

Operating System Details

No response

SQLModel Version

0.0.8

Python Version

3.9.16

Additional Context

No response