Getting Expected type expression but received "UnionType" from pyright when using model as type with v0.0.14

[ukalwa]

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Example Code

from typing import Optional

from sqlmodel import Field, Session, SQLModel, create_engine


class Hero(SQLModel, table=True):
    id: Optional[int] = Field(default=None, primary_key=True)
    name: str
    secret_name: str
    age: Optional[int] = None


hero_1 = Hero(name="Deadpond", secret_name="Dive Wilson")

engine = create_engine("sqlite:///database.db")


SQLModel.metadata.create_all(engine)

with Session(engine) as session:
    session.add(hero_1)
    session.commit()
    session.refresh(hero_1)
    print(hero_1)

def get_hero(user_id: int) -> Hero | None: # Pyright error here: Expected type expression but received "UnionType" 
    with Session(engine) as session:
        return session.exec(select(Hero).where(cls.id == user_id)).first()

Description

The issue seems to go away when I change the inheritance order in SQLModelMetaclass here

https://github.com/tiangolo/sqlmodel/blob/b892504141c842975b7a30156ab21755719e1d31/sqlmodel/main.py#L389-L390
to

class SQLModelMetaclass(DeclarativeMeta, ModelMetaclass): 
    __sqlmodel_relationships__: Dict[str, RelationshipInfo]

Operating System

macOS

Operating System Details

No response

SQLModel Version

0.0.14

Python Version

3.10.11

Additional Context

No response

[philippHorn]

I have the same issue in my codebase, for me it worked to use Optional[Model] instead of Model | None

[2jun0]

It works. Thank you

[mbertrand-kintsugi]

While this works, this is not technically correct. The | has been supported as a Union since Python 3.10. In our code, we accept either a None value or a "class instance" value. We don't provide a default, therefore Optional isn't correct. Instead we were forced to use Union[object, None] which is a lot more verbose to accomplish what already worked with object | None.

[9hgg]

@mbertrand-kintsugi , while I understand your point, Optional is equivalent to object | None.
Please see the snippet from the typing lib :