exclude() bug when used with Q() objects

[mucisland]

.exclude() behaves different when its argument is wrapped into Q(). Specifically, when wrapping an exclude filter with Q(), objects containing NULL in related fields are excluded as well as objects which have matching content in this field.

The SQL which is generated by exclude(<field>=<value>) should _not_ match objects with NULL in the respective field, but this is sometimes violated when wrapping the filter with Q(). (So far I've only seen this bug when using a filter which specifies a field in a related object.)

The attached file contains a minimum Django project (project name is "sandbox", application name is "q") with two test cases which should clarify the described behaviour.

Best Regards,
Dirk

[mucisland]

Django project "sandbox" with app "q" which reproduces the bug. Execute "manage.py test".

[Russell Keith-Magee]

I'm fairly certain that this is a duplicate of #11052; one of the examples in the comments seems to match up.

[jedediah@…]

Still seeing this in Django 1.4, so either it was erroneously marked as a dupe or it snuck back in. It's pretty simple to reproduce:

MyModel.objects.exclude(nullable_field=123)   => includes rows with nullable_field=null
MyModel.objects.exclude(Q(nullable_field=123))   => excludes rows with nullable_field=null

[Anssi Kääriäinen]

I tried this with master, one of the tests pass, the other doesn't. After the patch to #17600 this one would be fixed this.

I'm reopening this one so that proper test will be added in #17600.

[Anssi Kääriäinen]

This was fixed in d3f00bd5706b35961390d3814dd7e322ead3a9a3.