Class B

test/ext/test_associationproxy.py:1202–1208

                )

        class B(decl_base):
            __tablename__ = "b"
            id = mapped_column(Integer, primary_key=True)
            data = mapped_column(String)

            def __init__(self, data=None):
                self.data = data

        a1 = A()
        is_none(a1.b)