from sqlmodel import Field, SQLModel

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

In the above the type annotation for id is int but in the Field its mentioned that this column can have a default value of None

Then as per that it should be

    id: int | None = Field(default=None, primary_key=True)

or

    id: Optional[int] = Field(default=None, primary_key=True)