Question

I’m doing a single inheritance subclass for a django admin class like so:

from django.contrib.auth import admin as auth_admin

class UserAdmin(auth_admin.UserAdmin):
   pass

And I’m getting the error: “metaclass conflict: the metaclass of a derived class must be a (non-strict) subclass of the metaclasses of all its bases”

I think I understand what the error is complaining about – but I’m not clear on why I’m getting it with only a single ancestor. Every other time I’ve seen this error, it’s because I’m using multiple inheritance. What could the single ancestor’s class metaclass be conflicting with?

Answer 1

The issue turned out to be unrelated to the actual admin class – The form used for add_form must be a subclass of ModelForm – in this case it was just a plain Form. When added to the page django introspects the form and attempts to inject a class in if it’s not a ModelForm, leading the to the metatype mismatch.