admin.E202 seems to include superclass references?

[TorstenRottmann]

I have this three models defined:

class Act(models.Model):
    ....

class Form(Act):
    ...

class Diagnosis(Act):
    form = models.ForeignKey(Form)

...and this admin.py:

class DiagnosisInline(admin.TabularInline):
    model = Diagnosis
    ...

class FormAdmin(admin.ModelAdmin):
    ....
    inlines = [DiagnosisInline]

admin.site.register(Form, FormAdmin)

This triggers 'admin.E202':

<class 'nm.admin.DiagnosisInline'>: (admin.E202) 'nm.Diagnosis' has more than one ForeignKey to 'nm.Form'

Without looking into the source for this system check, I guess, that it counts all possible references, that lead to the admin class, the inline is included in.

And it counts two, from which one is right (Form) and one is wrong (Act), because it's already it's own superclass reference.

Am I right?

[Tim Graham]

There's no need to have the foreign key on Diagnosis as that model has an automatically created OneToOneField to Form because your models use ​multi-table inheritance.

[TorstenRottmann]

Well, that doesn't work. The inlines should be the Diagnosis, that point to a Form – and I simply can't manage that to work.
How is that done?

[Tim Graham]

Maybe what you meant to do is make Act an ​abstract base model. In that case, your original code should work fine.

For future reference, "is it a bug" type questions should be directed to our support channels at TicketClosingReasons/UseSupportChannels. Thanks!