How to create a basemodel with relationship?

[PaleNeutron]

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Example Code

from __future__ import annotations
from datetime import datetime
from typing import TYPE_CHECKING, Optional
from sqlalchemy import func

if TYPE_CHECKING:
    from .user import User  # noqa: F401

from sqlmodel import Field, Relationship, SQLModel


class EditableBase:
    create_time: datetime = Field(sa_column_kwargs=dict(server_default=func.now()))
    update_time: datetime = Field(sa_column_kwargs=dict(server_default=func.now(), onupdate=func.now()))
    create_id: int | None = Field(foreign_key="user.id")
    creator: Optional["User"] = Relationship(sa_relationship_kwargs=dict(foreign_keys=[create_id]))
    update_id: int | None = Field(foreign_key="user.id")
    updater: Optional["User"] = Relationship(sa_relationship_kwargs=dict(foreign_keys=[update_id]))

Description

I want to create a base class for every models in my project, all of them need creator and updater.

But if I use it as parent class of my model, this error appears:

<class 'app.models.user.User'> has no matching SQLAlchemy type

Operating System

Linux

Operating System Details

No response

SQLModel Version

0.0.16

Python Version

Python 3.10.12

Additional Context

this question is different with #488 , My basemodel is not a real table but just a "template"

[Ringostar1982]

You mean something like how to inherit ?
Class TokenUser and User will have "first_name" and "last_name" plus the fields declared in its classes too.

class BaseUser(SQLModel):
    first_name: str
    last_name: str


class TokenUser(BaseUser):   
    email: EmailStr = Field(default="[email protected]")
    locale: Optional[str]
    sub: Optional[str]
    subname: Optional[str]


class User(BaseUser, table=True):    
    __tablename__ = "users"
   division: Optional[str]
   department: Optional[str]

[joachimhuet]

I think you are just missing the parent class specification: class EditableBase(SQLModel)

But from experience it's not a good idea to define relationships in base class, it caused me so many problems.

Now I just put the type and default value for relationships in Base and specify the relationship in Table class. That is where it will actually be used anyway.

Example:

class EditableBase(SQLModel):
    create_time: datetime = Field(sa_column_kwargs=dict(server_default=func.now()))
    update_time: datetime = Field(sa_column_kwargs=dict(server_default=func.now(), onupdate=func.now()))

    creator: Optional["User"] = None
    updater: Optional["User"] = None

class EditableTable(EditableBase, table=True):
    # the ids are not used in schema, you can get them from creator.id or editor.id probably
    create_id: int | None = Field(foreign_key="user.id")
    update_id: int | None = Field(foreign_key="user.id")

    # in my experience the foreign_keys does not work properly saying create_id is not a Column so i use `primaryjoin` too
    creator: Optional["User"] = Relationship(sa_relationship_kwargs=dict(primaryjoin="EditableTable.create_id==UserTable.id"))
    updater: Optional["User"] = Relationship(sa_relationship_kwargs=dict(primaryjoin="EditableTable.update_id==UserTable.id"))

[PaleNeutron]

Thanks, leave a blank creator and updater in parent class is a great work!