I have two ORM models I’m migrating from SqlAlchemy 1.3 and it seems like the relationship is no longer working.

class SomeSpecialType:
    """Stores a SpecialType object as an str"""

    impl = types.String
    python_type = SpecialType

    def process_bind_param(
        self, value: Optional[SpecialType], dialect: Dialect
    ) -> Optional[str]:
        del dialect  # unused
        if value is not None:
            return value.value
        return None

    process_literal_param = process_bind_param

    def process_result_value(
        self, value: Optional[str], dialect: Dialect
    ) -> SpecialType:
        del dialect  # unused
        assert value is not None
        return SpecialType(value)

BaseModel: DefaultMeta = db.Model

class SomeModel(BaseModel):
    __tablename__ = 'some_table_name'
    id = Column(Integer, primary_key=True)
    str_column = Column(String(), nullable=False, index=True)
    special_type = Column(
        SomeSpecialType(),
        nullable=False,
        index=True,
        server_default=SpecialType.SPECIAL.value,
    )

    other_mode = relationship(
        'SomeOtherModel',
        cascade='delete',
        lazy='select',
        uselist=False,
        backref=backref('some_model', lazy='joined'),
    )


class SomeOtherModel(BaseModel):
    __tablename__ = 'some_other_table_name'
    id = Column(Integer, primary_key=True)
    some_model_id = Column(
        Integer, ForeignKey('some_table_name.id'), nullable=False, unique=True
    )
    int_column = Column(Integer, nullable=True)

I’m trying to rewrite my queries into SqlAlchemy 2.0 style to make it future compatible. My old query is:

created_other_model = SomeOtherModel.query.first()

I’ve swapped it to

some_other_select = select(SomeOtherModel, SomeModel).join(SomeModel)
self.assertEqual(db.session.scalar(select(func.count(SomeOtherModel.id))), 1)
some_other_instance = db.session.execute(cluster_config_select).scalar_one()

However, my assert in SomeSpecialType.process_result_value is saying the value is none which leads me to think that the columns from SomeModel are being included like they used to be with 1.3’s query

Thoughts on what I’m doing wrong with the query?