How to use Mixins? about sqlmodel

[elben10]

Try this out

from datetime import datetime
from typing import Optional

from pydantic import BaseModel
from sqlmodel import SQLModel, Column, DateTime, Field, Session, create_engine, select

        
class TimeStampMixin(BaseModel):
    created_at: Optional[datetime] = Field(
        sa_column=Column(
            DateTime,
            default=datetime.utcnow,
            nullable=False,
        )
    )

    updated_at: Optional[datetime] = Field(
        sa_column=Column(
            DateTime,
            default=datetime.utcnow,
            onupdate=datetime.utcnow,
        )
    )
    


class MyModel(SQLModel, TimeStampMixin, table=True):
    id: Optional[int] = Field(default=None, primary_key=True)
    name: str
        
engine = create_engine("sqlite:///database.db")
SQLModel.metadata.create_all(engine)

with Session(bind=engine) as session:
    session.add(MyModel(name="A Name"))
    session.commit()

[vi-klaas]

Why do we need to extend the Mixins from pydantic BaseModel and not SQLModel? Or is both possible? Also, with SQLModel, the definition would be simpler:

class TimeStampMixin(SQLModel):
    created_at: Optional[datetime] = Field(default=datetime.utcnow(), nullable=False)
    updated_at: Optional[datetime] = Field(default_factory=datetime.utcnow, nullable=False)

[lovetoburnswhen]

Try this out

from datetime import datetime
from typing import Optional

from pydantic import BaseModel
from sqlmodel import SQLModel, Column, DateTime, Field, Session, create_engine, select

        
class TimeStampMixin(BaseModel):
    created_at: Optional[datetime] = Field(
        sa_column=Column(
            DateTime,
            default=datetime.utcnow,
            nullable=False,
        )
    )

    updated_at: Optional[datetime] = Field(
        sa_column=Column(
            DateTime,
            default=datetime.utcnow,
            onupdate=datetime.utcnow,
        )
    )
    


class MyModel(SQLModel, TimeStampMixin, table=True):
    id: Optional[int] = Field(default=None, primary_key=True)
    name: str
        
engine = create_engine("sqlite:///database.db")
SQLModel.metadata.create_all(engine)

with Session(bind=engine) as session:
    session.add(MyModel(name="A Name"))
    session.commit()

That works! This also enables a Generic[_T] base class