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Diffstat (limited to 'docs/ref/contrib')
| -rw-r--r-- | docs/ref/contrib/contenttypes.txt | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/docs/ref/contrib/contenttypes.txt b/docs/ref/contrib/contenttypes.txt index c2e448329e..023db0b672 100644 --- a/docs/ref/contrib/contenttypes.txt +++ b/docs/ref/contrib/contenttypes.txt @@ -590,3 +590,29 @@ information. Subclasses of :class:`GenericInlineModelAdmin` with stacked and tabular layouts, respectively. + +.. module:: django.contrib.contenttypes.prefetch + +``GenericPrefetch()`` +--------------------- + +.. versionadded:: 5.0 + +.. class:: GenericPrefetch(lookup, querysets=None, to_attr=None) + +This lookup is similar to ``Prefetch()`` and it should only be used on +``GenericForeignKey``. The ``querysets`` argument accepts a list of querysets, +each for a different ``ContentType``. This is useful for ``GenericForeignKey`` +with non-homogeneous set of results. + +.. code-block:: pycon + + >>> bookmark = Bookmark.objects.create(url="https://www.djangoproject.com/") + >>> animal = Animal.objects.create(name="lion", weight=100) + >>> TaggedItem.objects.create(tag="great", content_object=bookmark) + >>> TaggedItem.objects.create(tag="awesome", content_object=animal) + >>> prefetch = GenericPrefetch( + ... "content_object", [Bookmark.objects.all(), Animal.objects.only("name")] + ... ) + >>> TaggedItem.objects.prefetch_related(prefetch).all() + <QuerySet [<TaggedItem: Great>, <TaggedItem: Awesome>]> |