Class A

test/ext/test_associationproxy.py:1184–1200

        self, create_on_none, specify_creator, decl_base
    ):
        class A(decl_base):
            __tablename__ = "a"
            id = mapped_column(Integer, primary_key=True)
            b_id = mapped_column(ForeignKey("b.id"))
            b = relationship("B")

            if specify_creator:
                b_data = association_proxy(
                    "b",
                    "data",
                    create_on_none_assignment=bool(create_on_none),
                    creator=lambda data: B(data=data),
                )
            else:
                b_data = association_proxy(
                    "b", "data", create_on_none_assignment=bool(create_on_none)
                )

        class B(decl_base):
            __tablename__ = "b"