Support custom admin classes in @admin.register fixer

[UnknownPlatypus]

For #190

Hey, so I started working on the custom admin support and I had a few interrogations to finish it.

1. Is a stacked syntax ok when the same admin model is used to register a model against different sites ?

class MyAdminSite(admin.AdminSite):
    site_header = "My very custom administration"

custom_site = MyAdminSite(name="myadmin")

+@admin.register(Comment)
+@admin.register(Comment, site=custom_site)
class CommentAdmin(admin.ModelAdmin):
    pass


-admin.site.register(Comment, CommentAdmin)
-custom_site.register(Comment, CommentAdmin)

2. What should I do if from django.contrib import admin is missing (I suppose it's quitte common if you work with custom sites). I'm not sure where to add the import

3. Should we extend the looks_like_admin_file check heuristic to the regular fixers too ?

[adamchainz]

1. Is a stacked syntax ok when the same admin model is used to register a model against different sites ?

class MyAdminSite(admin.AdminSite):
    site_header = "My very custom administration"

custom_site = MyAdminSite(name="myadmin")

+@admin.register(Comment)
+@admin.register(Comment, site=custom_site)
class CommentAdmin(admin.ModelAdmin):
    pass
-admin.site.register(Comment, CommentAdmin)
-custom_site.register(Comment, CommentAdmin)

This seems fine to me - the decorator returns the admin class, unchanged, so that should work.

2. What should I do if `from django.contrib import admin` is missing (I suppose it's quitte common if you work with custom sites). I'm not sure where to add the import

I don't think we need to handle this case. It's idiomatic to import admin in order to subclass admin.ModelAdmin.

3. Should we extend the `looks_like_admin_file` check heuristic to the regular fixers too ?

I think it's fine to rely on the admin import in those cases.

[UnknownPlatypus]

Great, thanks for the quick response.

Then I suppose you can check the code.
Your answers are matching the assumptions I made 😄

If was thinking the changelog and docs are still relevant but let me know if you want me to add a mention somewhere of the different extensions to the initial fixer.

Cheers.

[adamchainz]

I don't think the changelog needs updating but the readme could do with another example for cusotm sites, and maybe a sentence describing how custom sites are detected.

[adamchainz]

Alright, looks good to merge. I've pushed a few small fixes, including support files with names like custom_admin.py. This is the most common pattern I've seen, where a projcet might have a main admin with classes in admin.py files, then a second admin site with its classes in <name>_admin.py files.