Using get_object_or_404 on a class that isn't a Django model could result in a more obvious error message.

[Kit Sunde]

I have a Calendar model in my app but I wrongly imported calendar.Calendar from python instead which resulted in:

type object 'Calendar' has no attribute '_default_manager'

Which led me to think it was this issue: https://code.djangoproject.com/ticket/10405 perhaps it would be possible to raise a ValueError if get_object_or_404 receives something that is not of the correct type with "type object 'Calendar' is not a Django Model".

In _get_queryset it seems like it should raise a ValueErorr if it is not a Model, Manager, or QuerySet if that is what it expects, rather than to assume it is a Model if it's not the other two as it is now.

Or perhaps it was just PEBCAK on my part. :)

[atykhonov]

I'm sorry, I'm not sure, but I think that this is not an issue...
That error "type object 'Calendar' has no attribute '_default_manager'" obviously makes me think that passed object is of wrong type....

[Claude Paroz]

It wouldn't cost much to wrap the klass._default_manager line into a try... except clause.

[BHold]

Submitted pull request -- ​https://github.com/django/django/pull/581

Passes all tests.

[Claude Paroz]

Thanks! I think you only missed the case where a non-model class name is passed to get_object_or_404. I will just add that and commit the patch.

[Claude Paroz <claude@…>]

In 6ed6a18a033ba78de9418f5b56b80f8b3d3aaf11:

Fixed #19432 -- Provided better error message for get_object_or_404

Thanks Kit Sunde for the report and Brian Holdefehr for the initial
patch.

[Claude Paroz <claude@…>]

In c20c3a20a313b24df6d115e585c04c8dc60d3970:

[1.5.x] Fixed #19432 -- Provided better error message for get_object_or_404

Thanks Kit Sunde for the report and Brian Holdefehr for the initial
patch.
Backport of 6ed6a18a0 from master.