Fixed #24019 -- Fixed inaccurate docs about GenericRelation not supporting aggregation.

Generic relations and aggregation

---------------------------------

:doc:`Django's database aggregation API </topics/db/aggregation>`

doesn't work with a

:doc:`Django's database aggregation API </topics/db/aggregation>` works with a

:class:`~django.contrib.contenttypes.fields.GenericRelation`. For example, you

might be tempted to try something like::

can find out how many tags all the bookmarks have::

    Bookmark.objects.aggregate(Count('tags'))

This will not work correctly, however. The generic relation adds extra filters

to the queryset to ensure the correct content type, but the

:meth:`~django.db.models.query.QuerySet.aggregate` method doesn't take them

into account. For now, if you need aggregates on generic relations, you'll

need to calculate them without using the aggregation API.

    >>> Bookmark.objects.aggregate(Count('tags'))

    {'tags__count': 3}

.. module:: django.contrib.contenttypes.forms