Extensions to @admin.register fixer

[adamchainz]

Description

Following #182 / #189 , there are a few more cases that could be covered with further work.

1. Support kwarg form ✅ Support admin_class as keyword argument in @admin.register fixer #192

+@admin.register(MyModel)
 class MyModelAdmin(...):
    ...

-admin.site.register(MyModel, admin_class=MyModelAdmin)

2. Support multiple models ✅ Support multiple model classes in @admin.register fixer #200

+@admin.register(Model1, Model2)
 class MyModelAdmin(...):
    ...

-admin.site.register(Model1, MyModelAdmin)
-admin.site.register(Model2, MyModelAdmin)

+@admin.register(Model1, Model2)
 class MyModelAdmin(...):
    ...

-admin.site.register((Model1, Model2), MyModelAdmin)

3. Support when there are other class decorators, insert at top ✅ Support stacking class decorator in @admin.register fixer #193

+@admin.register(MyModel)
 @something
 class MyModelAdmin(...):
    ...

-admin.site.register(MyModel, MyModelAdmin)

4. Support custom admin sites ✅ Support custom admin classes in @admin.register fixer #228

from myapp.admin import custom_site

+@admin.register(MyModel, site=custom_site)
 class MyModelAdmin(...):
    ...

-custom_site.register(MyModel, MyModelAdmin)

• detect custom site objects heuristically, to avoid affecting other code that uses a 'register' pattern, perhaps when the object's name ends in 'site', and the registered class name ends in 'Admin' (and maybe the file looks like an admin file, called "admin.py" or in an "admin" directory?)

5. Also work for from django.contrib.gis import admin - ✅ Support admin import from gis in @admin.register fixer #204
   This imports the register decorator for convenience when authoring GIS apps.

[adamchainz]

@UnknownPlatypus I have entertained myself tackling the two easiest ones here, perhaps you'd like to try the other two?

[UnknownPlatypus]

@adamchainz Absolutely, would be nice to work on that and I think I have some ideas on how to tackle them.

[adamchainz]

@UnknownPlatypus added point 5 above as well, for GIS admins.

[adamchainz]

Alright we've checked everything off from this list! 🥳

This is now a really awesome feature that covers many cases. Great work @UnknownPlatypus .

[UnknownPlatypus]

Thank again @adamchainz for the continuous support along the way and the kind help with my first few contributions to the open source community. 🙏