# DB models 

class Role:
    id = IdField()
    name = StrField()
    description = TextField()

class User:
    id = IdField()
    username = StrField()
    password = StrField()
    role = ReferenceField(Role)

# GraphQL types
@strawberry.type
class UserRead:
    id: str
    username: str

@strawberry.type
class RoleRead:
    id: str
    name: str

@strawberry.type
class TaskRead:
    assignee: UserRead | RoleRead | None = StrawberryField(db_model_graphql_type_mapping={
        User: UserRead, Role: RoleRead
    })
    title: str
    content: str
    due_at: datetime

class StrawberryField:
    def __init__(
        self,
        db_model_graphql_type_mapping: dict[Any, Any] | None = None,
       # other parameters
    ):
        self.db_model_graphql_type_mapping = db_model_graphql_type_mapping
        # other stuff

    def get_result(
        self, source: Any, info: Optional[Info], args: list[Any], kwargs: dict[str, Any]
    ):
        """
        Calls the resolver defined for the StrawberryField.
        If the field doesn't have a resolver defined we default
        to using the default resolver specified in StrawberryConfig.
        """
        if self.db_model_graphql_type_mapping:
            return self.convert_to_graphql_type(source)

        if self.base_resolver:
            return self.base_resolver(*args, **kwargs)

        return self.default_resolver(source, self.python_name)
    
    def convert_to_graphql_type(self, source: Any)
        db_object = getattr(source, self.name)
        if not db_object:
            return

        db_model = type(db_object)
        graphql_type = self.db_model_graphql_type_mapping[db_model]
        fields = graphql_type.__dict__["__dataclass_fields__"].keys()
        return graphql_type(**{f: getattr(db_object, f) for f in fields})