MissingReturnAnnotationError

[cog-roym]

Describe the Bug

Receiving the following error:

strawberry.exceptions.missing_return_annotation.MissingReturnAnnotationError

When trying to use inheritance with the Strawberry models and SQLAlchemy model relationships. I have a very contrived example below but while the error is a bit confusing i'm not sure what the desired behaviour should be.
Should the mapper be able to handle inheritance?

from sqlalchemy.orm import (
    DeclarativeBase,
    relationship,
    Mapped,
    mapped_column,
)
from sqlalchemy import ForeignKey
 
from strawberry_sqlalchemy_mapper import StrawberrySQLAlchemyMapper
 
strawberry_sqlalchemy_mapper = StrawberrySQLAlchemyMapper()
 
class Base(DeclarativeBase):
    pass
 
class ModelA(Base):
    __tablename__ = "a"
 
    id: Mapped[str] = mapped_column(primary_key=True)
 
    relationshipB_id: Mapped[str] = mapped_column(ForeignKey(f"b.id"))
    relationshipB: Mapped["ModelB"] = relationship()
 
class ModelB(Base):
    __tablename__ = "b"
 
    id: Mapped[str] = mapped_column(primary_key=True)
 
    relationshipB_id: Mapped[str] = mapped_column(ForeignKey(f"b.id"))
    relationshipB: Mapped["ModelB"] = relationship()
 
@strawberry_sqlalchemy_mapper.type(ModelA)
class ApiA:
    pass
 
@strawberry_sqlalchemy_mapper.type(ModelB)
class ApiB(ApiA):
    pass

System Information

• Operating system: windows
• Strawberry version (if applicable): 0.268.1 / 0.6.1

Additional Context

[Ckk3]

Hi, @cog-roym , I've tested your code (on a linux machine) and its worked, maybe you forget to call strawberry_sqlalchemy_mapper.finalize()?

The code test I've used.

from sqlalchemy import orm
from sqlalchemy.orm import (
    relationship,
    Mapped,
    mapped_column,
)


@pytest.fixture
def base():
    return orm.declarative_base()


@pytest.fixture
def mapper():
    return StrawberrySQLAlchemyMapper()


@pytest.fixture
def inheritance_table(base):
    class ModelA(base):
        __tablename__ = "a"

        id: Mapped[str] = mapped_column(primary_key=True)

        relationshipB_id: Mapped[str] = mapped_column(ForeignKey("b.id"))
        relationshipB: Mapped["ModelB"] = relationship()

    class ModelB(base):
        __tablename__ = "b"

        id: Mapped[str] = mapped_column(primary_key=True)

        relationshipB_id: Mapped[str] = mapped_column(ForeignKey("b.id"))
        relationshipB: Mapped["ModelB"] = relationship()

    return ModelA, ModelB


def test_inheritance_table(inheritance_table, mapper):
    ModelA, ModelB = inheritance_table

    @mapper.type(ModelA)
    class ApiA:
        pass

    @mapper.type(ModelB)
    class ApiB(ApiA):
        pass

    @strawberry.type
    class Query:
        @strawberry.field
        def apisb(self) -> ApiB: ...

        @strawberry.field
        def apisa(self) -> ApiA: ...

    mapper.finalize()
    schema = strawberry.Schema(query=Query)
    # >>> str(schema)
    # type ApiA {
    #     id: String!
    #     relationshipBId: String!
    #     relationshipB: ModelB!
    # }
    #
    # type ApiB {
    #     id: String!
    #     relationshipBId: String!
    #     relationshipB: ModelB!
    # }
    #
    # type ModelB {
    #     id: String!
    #     relationshipBId: String!
    #     relationshipB: ModelB
    # }
    #
    # type Query {
    #     apisb: ApiB!
    #     apisa: ApiA!
    # }

[cog-roym]

Thank for looking at this.

It seems to be dependent on the python version.

fails with 3.10
works with 3.9

[Ckk3]

@cog-roym Wow, this is new... I will create a new PR to run the CI with this new test to check if there's anothers python versions it fails (our CI tests runs from 3.8 to 3.13).

Do you find another way to replicate this issue, or only with python version?

[cog-roym]

Hey,
I was a bit of a guess to test python versions. I first started looking at all the dependencies without reproducing it.

[Ckk3]

@cog-roym I will start working on a solution to this issue on this PR #253 .
Please fell free to give me any idea you has to fix it 😉