FieldError when using select_related with enable_only_optimization

[blueyed]

When trying to use select_related on a field, I am getting an error when the DjangoOptimizerExtension is used with its default enable_only_optimization=True.

This happens because only() is used with "id", and then select_related is issued on top: https://github.com/blb-ventures/strawberry-django-plus/blob/9a54dd0378b31302b99754704ccd9f1025f43fbd/strawberry_django_plus/optimizer.py#L529-L533

django.core.exceptions.FieldError: Field Foo.bar cannot be both deferred and traversed using select_related at the same time.

A workaround is to add the field also to only, but that could be done automatically then also.

@django_type(models.Foo, filters=FooFilter, pagination=True)
class Foo:
    bar: Bar
    special_bar: Bar | None = gql.django.field(
        only=["bar"],  # workaround
        select_related=["bar"]
    )

I am not sure about the select_related being necessary/useful here yet (maybe because of the Optional/None it might be necessary), but I think it's a generic issue.

I also wondered what's the point of enable_only_optimization. Is it to reduce the amount of data being selected/transferred only?

(related)