admin.site.register() does not check if the model is abstract (gives weird error)

[Diederik van der Boor]

When an abstract model is registered with admin.site.register() it produces the following error later on:

type object '...' has no attribute '_default_manager'

This error does not make much sense unless you're already have more intimate knowledge of the framework.
To ease the learning curve of new developers, I think it would make sense to check whether the model is abstract or not.

[Diederik van der Boor]

Addition: it produces even more weird errors in the admin_tools dashboard, when viewing a specific app:

Caught AttributeError while rendering: 'NoneType' object has no attribute '_meta'

which happens somewhere in the contenttypes framework:

File "/usr/lib/python2.6/site-packages/admin_tools/dashboard/templatetags/admin_tools_dashboard_tags.py" in admin_tools_render_dashboard_css
  90.         dashboard = get_dashboard(context, location)
File "/usr/lib/python2.6/site-packages/admin_tools/dashboard/utils.py" in get_dashboard
  21.         return get_app_index_dashboard(context)
File "/usr/lib/python2.6/site-packages/admin_tools/dashboard/utils.py" in get_app_index_dashboard
  71.     return getattr(mod, inst)(app_title, model_list)
File "/usr/lib/python2.6/site-packages/admin_tools/dashboard/dashboards.py" in __init__
  304.             include_list=self.get_app_content_types(),
File "/usr/lib/python2.6/site-packages/admin_tools/dashboard/dashboards.py" in get_app_content_types
  184.                 in self.get_app_model_classes()]
File "/usr/lib/python2.6/site-packages/django/contrib/contenttypes/models.py" in get_for_model
  40.             self._add_to_cache(self.db, ct)
File "/usr/lib/python2.6/site-packages/django/contrib/contenttypes/models.py" in _add_to_cache
  70.         key = (model._meta.app_label, model._meta.object_name.lower())

[rasca]

I can confirm that it outputs this error.

[Craig de Stigter]

Prevent registration of abstract models with AdminSite.register(). Includes regression test

[Julien Phalip]

This was fixed in [15636].