remove generics from QuerySet type

[jerch]

See #704 - currently it is not possible to deal with QuerySet class obj in python without getting a generics alert. By removing the [_T, _T] it works again without complaints.

Related issues

Closes #704.

I have no idea about possible side effects of this change, so please someone with more knowledge about the typing internals of django-stubs would have to review this change.

[sobolevn]

Maybe like this?

class QuerySet(_QuerySet[_T, _T]): ...

Or:

class _QuerySetAlias(_QuerySet[_T, _T]): ...

QuerySet = _QuerySetAlias

[jerch]

@sobolevn Yes, trying your first variant (as it looks nicer to me). Still I wonder if the queryset base class has a model base class connection at all (have not looked up the django source). In the end it does not matter as long as the interfaces with types are announced correctly.

[sobolevn]

Thanks! We still need a test case for #704

[jerch]

@sobolevn Are those explicit tests against _QuerySet[XY, XY] needed or can they be replaced by QuerySet[XY]? Would that lose test/type information?

[sobolevn]

Are those explicit tests against _QuerySet[XY, XY] needed

Yes, we need them to test our internal representation of QuerySet, which is needed for things like .annotate() to work.

[jerch]

@sobolevn Not sure if I can help you with the test cases. I am getting tons of errors, if I try to run pytest locally in a venv with python 3.10 (bootstrapped similar to the CI setup), like these:

/home/jerch/Dokumente/github/django-stubs/tests/typecheck/test_config.yml:5: 
E   pytest_mypy_plugins.utils.TypecheckAssertionError: Invalid output: 
E   Actual:
E     ../../home/jerch/Dokumente/github/django-stubs/django-stubs/db/models/deletion.pyi:12: error: Bad number of arguments for type alias, expected: 2, given: 1 (diff)

<here like 30 more errors of the same type in other places>

E     main:3: note: Revealed type is "builtins.int*" (diff)
E     main:4: note: Revealed type is "django.contrib.auth.models.User*" (diff)
E     main:5: note: Revealed type is "django.db.models.manager.Manager[myapp.models.MyModel]" (diff)
E     myapp/models:6: note: Revealed type is "django.contrib.auth.models.User*" (diff)
E   Expected:
E     main:3: note: Revealed type is "builtins.int*" (diff)
E     main:4: note: Revealed type is "django.contrib.auth.models.User*" (diff)
E     main:5: note: Revealed type is "django.db.models.manager.Manager[myapp.models.MyModel]" (diff)
E     myapp/models:6: note: Revealed type is "django.contrib.auth.models.User*" (diff)
E   Alignment of first line difference:
E     E: main:3: note: Revealed type is "builtins.int*"...
E     A: ../../home/jerch/Dokumente/github/django-stubs/django-stubs/db/models/de...
E        ^

[intgr]

I tried this change and it causes new errors in my code. For example:

            MyModel.objects.annotate(
                last_status=Subquery(
                    OtherModel.objects.values("last_status")
                )

error: Argument 1 to "Subquery" has incompatible type "_QuerySet[OtherModel, TypedDict({'last_status': str})]"; expected "QuerySet[Any]"

Because _QuerySet and QuerySet are now distinct types, _QuerySet cannot be converted to its subclass QuerySet.

I think some changes are needed in the plugin code as well.

[jerch]

@intgr Thats the reason why I asked if QuerySet[XY] could replace _QuerySet[XY, XY]. But your use case already answers that as a clear no (see the different types in _QuerySet[OtherModel, TypedDict({'last_status': str})]. Sadly I cannot get the test cases working locally, thus cannot do much to get things fixed.

[intgr]

This seems redundant now that #794 has been merged?

Feel free to re-open if I'm missing something.