let proxy models multiple-inherit from the same concrete base model

[Ryan Kelly]

Currently proxy models are required to have a single concrete base model class. Unfortunately this prevents me from combining several proxy subclasses of the same model. In my particular use case, I have two different apps that provide two different proxies of the standard User model. To successfully use both apps I need to create another subclass that combines the two, e.g:

class MyUser(App1User,App2User):
    class Meta:
        proxy = True

This gives a TypeError: "Proxy model 'MyUser' has more than one non-abstract model base class". But since App1User and App2User proxy the same underlying model, there's no ambiguity introduced by this multiple inheritance and I think it should be permitted.

Attached is a simple patch to make this work, by permitting additional concrete base classes if they are identical to the one that was already found.

[Julien Phalip]

The tests would need to be rewritten using unittests since this is now Django's preferred way.

[Ryan Kelly]

I've redone the patch against latest trunk and added a brief note in the proxy models documentaion.

[Aymeric Augustin]

Change UI/UX from NULL to False.

[Aymeric Augustin]

Change Easy pickings from NULL to False.

[gzerone@…]

Hi rfk, thanks for the patch file, it works for me. Hope the feature will work on master branch.

[Griatch]

This has been lurking around for a long time, any idea when this might merge into master? The patch seems to have unittest information now and the feature itself is working. We would much like to use this feature without having to patch django itself.

[Tim Graham]

The patch needs to be updated to apply cleanly. If you can update it and send a pull request, that will help. Also a mention in the release notes and a .. versionchanged:: 1.8 annotation would be helpful. See our ​patch review checklist.

[Asif Saifuddin Auvi]

Replying to timgraham:

The patch needs to be updated to apply cleanly. If you can update it and send a pull request, that will help. Also a mention in the release notes and a .. versionchanged:: 1.8 annotation would be helpful. See our ​patch review checklist.

Hi Tim,

Is this issue already resolved by other works ? or I should work on the patch to implement it cleanly?

[Tim Graham]

I don't know of any work that would have resolved this ticket.

[Akshesh Doshi]

PR: ​https://github.com/django/django/pull/6346/

[Tim Graham]

Left a few comments for improvement.

[Tim Graham <timograham@…>]

In 49f95cc0:

Fixed #11560 -- Allowed proxy model multiple-inheritance from the same concrete base model.