from sqlalchemy import Column from sqlalchemy import Integer from sqlalchemy import String from sqlalchemy.orm import declarative_base from sqlalchemy.orm import registry reg: registry = registry() Base = declarative_base() class SomeAbstract(Base): __abstract__ = True class HasUpdatedAt: updated_at = Column(Integer) @reg.mapped class Foo(SomeAbstract): __tablename__ = "foo" id: int = Column(Integer(), primary_key=True) name: str = Column(String) class Bar(HasUpdatedAt, Base): __tablename__ = "bar" id = Column(Integer(), primary_key=True) num = Column(Integer) Bar.__mapper__ # EXPECTED_MYPY: "Type[HasUpdatedAt]" has no attribute "__mapper__" HasUpdatedAt.__mapper__ # EXPECTED_MYPY: "Type[SomeAbstract]" has no attribute "__mapper__" SomeAbstract.__mapper__