Fix 1061: DjangoListField should not cache queries

[zbyte64]

Attempt to fix #1061

1. test that default functionality should resolve/call queryset at view time
2. DjangoListField.get_default_queryset returns a manager and list_resolver calls maybe_queryset on default_queryset

[zbyte64]

Not sure if this is how we want to fix the issue, seems to me default_queryset should be a callable to be called during view execution time.

[tcleonard]

The problem comes from line 71

    def get_resolver(self, parent_resolver):
        _type = self.type
        if isinstance(_type, NonNull):
            _type = _type.of_type
        django_object_type = _type.of_type.of_type
        return partial(
            self.list_resolver,
            django_object_type,
            parent_resolver,
            self.get_default_queryset(), # <<<< This gets evaluated on init
        )

Your change basically move the execution to later by making not return a queryset but the queryset manager (that you then force the evaluation via maybe_queryset).
I think it's a bit convoluted. And it's a bit confusing to call it get_default_queryset when we already know it does not return a queryset...

I would change it to something like:

    def default_queryset_resolver(self):
        return self.model._default_manager.get_queryset

    @staticmethod
    def list_resolver(
        django_object_type, resolver, default_queryset_resolver, root, info, **args
    ):
        queryset = maybe_queryset(resolver(root, info, **args))
        if queryset is None:
            queryset = default_queryset_resolver()

        if isinstance(queryset, QuerySet):
            # Pass queryset to the DjangoObjectType get_queryset method
            queryset = maybe_queryset(django_object_type.get_queryset(queryset, info))

        return queryset

    def get_resolver(self, parent_resolver):
        return partial(
            self.list_resolver,
            self._underlying_type,   # Do you see any reason why we were not doing that here? if there is a good reason you can change it back
            parent_resolver,
            self.default_queryset_resolver()
        )

[zbyte64]

I agree the naming is wrong. I don't want to drop get_default_queryset as that is documented in the API, so going forward I think we'll have default_queryset_resolver return get_default_queryset which seems a tad odd. Also wondering if we should incorporate info to be passed to the default_queryset_resolver callable.

[tcleonard]

[...] we'll have default_queryset_resolver return get_default_queryset which seems a tad odd

I assume you mean the other way around?
If you want to keep the function get_default_queryset I would simply add it as:

def self.get_default_queryset(self):
    return default_queryset_resolver()()

which is still weird.... :)

But I don't necessarily see the point if it is not used.
You say it's in the documentation but I couldn't find it... all I see is reference to get_queryset on DjangoObjectType which is the method we call here (so if a user had overridden it, it would still work).

[zbyte64]

Huh, you're right about the docs. Also in the same file we have DjangoConnectionField which defines resolve_queryset & get_queryset_resolver as well as get_manager which acts as the default queryset. I like the semantics there more, maybe it should adopt those methods, certainly asking for a default manager instead of a queryset is a better contract that prevent caching

[tcleonard]

Makes sense 👍
Did you see my comment/question about why we are not using self._underlying_type in the get_resolver() method?