Registering abstract model with admin gives confusing / misleading error

[Matt Smalley <matt.smalley@…>]

It makes perfect sense that an abstract model cannot be registered with admin. However, the abstract model is listed with the rest and there is no error until the page for that model is requested from the admin interface. Doing so gives:

'str' object has no attribute '_default_manager'

This is a bit mysterious, and IMO would be better handled at the time of registering the model with something more explicit. Also, since this error occurs in some other hard-to-identify cases (see ​#10405, among others), I spent a lot of time going down blind alleys in search of the source of the problem.

[Matthias Kestenholz]

This patch changes admin.site.register to raise an ImproperlyConfigured exception if someone tries to register an abstract model with the administration.

Unit test included.

[Julien Phalip]

Patch with correct diff extension

[Julien Phalip]

Thank you mk for your patch. I've just updated the message in the exception and simplified the tests (no need to have a special url or AdminSite object).

[Julien Phalip]

Simplified test and move it to a better home (regressiontests/admin_registration/)

[Russell Keith-Magee]

In [15636]:

Fixed #12004 -- Improved error reporting when an abstract class is registered with the admin. Thanks to Matt Smalley for the report, and to mk and Julien Phalip for the patch.

[Jacob]

Milestone 1.3 deleted