Query optimization based on type hints for non-model fields?

[blueyed]

A field that represents a model property will not be handled by the query optimizer:

strawberry-django-plus/strawberry_django_plus/optimizer.py

Lines 163 to 166 in 9a54dd0

	# Lastly, from the django field itself
	model_fieldname: str = getattr(field, "django_name", None) or field.python_name
	model_field = model_fields.get(model_fieldname, None)
	if model_field is not None:

It could get derived from the type hint though, couldn't it?

Specifying field_name, which gets translated into django_name works.
Is this supposed to work like/for this?
Are there unwanted side effects given that it is of type Foo, but not necessarily the actual foreign key / linked object?

    special_foo: Foo = gql.django.field(
        field_name="foo",  # workaround? other side effects?
    )

As for now I am happy with adding only/select_related manually (related: #152).

[blueyed]

side effects?

There are..

For now I can work with using only={"foo__archived"}, to help the function, which uses that property.

[bellini666]

Hey @blueyed ,

Hrm, we can probably try to do something like that. But having said that, have you take a look at model properties?

You can use it to create a @property in your model, and it accepts optimizer hints. Then on your type you can use that_property_attr: auto. I use that a lot!

[blueyed]

@bellini666
I think model properties do not help here: the issue is that there is a property, which returns a special "Bar" object via a property/function, and the optimizer does not automatically apply prefetch_related for related objects from there (although the return type indicates that).

My workaround now is to use get_queryset:

@django_type(models.StageRecipe, filters=StageRecipeFilter, pagination=True)
class Bar:
    bar: Bar

    @gql.django.field(
        select_related=[
            "foo__current_version",
        ],
        only=[
            "foo__current_version",
        ],
    )
    def current_foo(self) -> Foo | None:
        return self.foo.current_version

    @classmethod
    def get_queryset(cls, queryset, info, **kwargs):
        qs = queryset.exclude(operational_recipe__status=RecipeStatus.DRAFT)

        for selected_field in info.selected_fields:
            if selected_field.name != "bars":
                continue
            for selected_field2 in selected_field.selections:
                if selected_field2.name != "currentFoo":
                    continue
                for selected_field3 in selected_field2.selections:
                    if selected_field3.name == "baz":
                        qs = qs.prefetch_related("Foo__current_version__baz")

        ...
        return qs

@django_type(
    models.Bar,
    pagination=True,
    only=[
        "status",  # for ConcurrentTransitionMixin.
        "current_version",
    ],
)
class Bar:
    baz: list["Bar"]

[bellini666]

Hrmm, that __baz is inside a hint and not being discovered by the automatic optimizer

I probably need to find a way to handle those.