ModelAdmin for model with InlineModelAdmin for proxy class reference results in admin.E202

[Quinten Kock]

This is similar to #30273 and #32975. A class references a proxy model, and we define an inline for the proxied model. This fails with admin.E202 because Django does not recognize that the FK to the proxy model is the same as an FK to the proxied model.

Assume models as follows:

class Reporter(models.Model):
    name = models.CharField(max_length=50)

class Journalist(Reporter):
    class Meta:
        proxy = True

class Article(models.Model):
    reporter = models.ForeignKey(Journalist, on_delete=models.CASCADE)

and an admin as follows:

class ArticleInline(admin.TabularInline):
    model = Article
    fk_name = 'reporter'

@admin.register(Reporter)
class ReporterAdmin(admin.ModelAdmin):
    inlines = [ArticleInline]

This will result in <class 'testapp.admin.ArticleInline'>: (admin.E202) fk_name 'reporter' is not a ForeignKey to 'testapp.Reporter'.

The problem seems to be that the parent list does not include the model itself, and as such Django does not recognize the equality here.

[Asfand Yar Khan]

Was able to reproduce this on my end.

[Antoine Cheneau]

Made a PR here: ​https://github.com/django/django/pull/17435

[Mariusz Felisiak <felisiak.mariusz@…>]

In 65c283b:

Fixed #34927 -- Fixed admin system check for inlines with foreign keys to proxy models.

Follow up to 0e8be73812a6e62d5a6b12a585d133b56bc2bf52.