Allow for easier QuerySet customization.

[floguy]

The impetus for this patch is that it will be difficult for the built-in QuerySet implementation to satisfy everyone's needs (as evidenced by some vehement disagreements about aggregate functionality on django-dev).

Currently the only way to really deal with this is to fork Django and keep a local copy up to date.

This patch allows for the specification of a default QuerySet class (which can be located anywhere on the PythonPath) which will be used in all query operations. To add group_by functionality, for example, one could subclass django.db.models.query.BaseQuerySet and add a group_by function. Then, specify DEFAULT_QUERYSET_CLASS to be the path to your custom subclass. Now group_by would be available in all filters, managers, etc. without ever having forked Django.

In fact, there could now be a whole host of externally-hosted QuerySet subclasses, and therefore new ideas could be more easily experimented with.

Thoughts? Ideas? Should I bring this up on django-dev?

[floguy]

By the way, I'm completely at a loss for how to test this, as settings don't seem to be able to be reconfigured on-the-fly.

[David Cramer]

from django.conf import settings
settings.HI = 1

[floguy]

dcramer: I'm not sure exactly what that was supposed to mean. An accidental submit?

[David Cramer]

Sorry, should have been on two lines, but you can import the settings in such a manner to reconfigure most settings "on the fly" as you put it.

[Jacob]

wontfix -- see ​the discussion on django-dev.