Allow single generic param for Field in ForeignKey

[rafonseca]

Allow a less verbose specification of foreign keys

This set he default type of getter so that the user can choose to specify the foreign key using one or two generic params.

Recently, I've moved from django-types to django-stubs, and this modification allowed for a smooth transition.

Related issues

• Refs Use django-stubs with type checkers other than mypy #579
• Refs Feature: Use PEP 696 defaults for fields #1264

[flaeppe]

This looks fine to me but a bunch of plugin code is about/around these _ST and _GT type variables so for that reason and any future changes, I would like that a test is included here that uses a single generic argument. Would be great if both OneToOneField and ForeignKey are included in that test

[sobolevn]

Yes, please, add a test for single-arg Field

[rafonseca]

I've forgot to mention I used this with pyright... I'm not acquainted with mypy but what I understand here is that either mypy does not propagates the type defined in the first parameter to the second parameter or it is a printing issue. In the latter case, maybe there is another way to write the test.
@sobolevn , @flaeppe , can you give me some advice here?

[flaeppe]

I think it's the former, mypy not handling type vars as default, while recognizing what you say from python/mypy#14851 (comment)

Our own related issue is #1264

[flaeppe]

Since Mypy doesn't seem to break by adding the default= argument I would be fine adding it already for the sakes of pyright.

Which hopefully allows us to just fill in for Mypy later on when python/mypy#14851 (comment) is resolved

We could add expect_fail: true (xfail) for the 2 new tests to start with

[rafonseca]

Thanks for the quick answer @flaeppe . I've updated with your suggestions. Should we add any note about the failing test or the link to this PR in the final commit message is enough?

[flaeppe]

No need to add a note, I feel like the git history and link to this PR will be enough.