mirrors/django
1
0
Fork 0
mirror of https://github.com/django/django.git synced 2025-08-04 02:48:35 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 1

Fixed #25279 -- Made prefetch_related_objects() public.

Browse source
This commit is contained in:
Adam Chainz 2015-08-15 13:41:57 +01:00 • committed by Tim Graham
parent d5f89ff6e8
commit ef33bc2d4d
5 changed files with 155 additions and 12 deletions
Download patch file Download diff file Expand all files Collapse all files

26
docs/ref/models/querysets.txt
View file

@ -920,6 +920,10 @@ results; these ``QuerySets`` are then used in the ``self.toppings.all()`` calls.
The additional queries in ``prefetch_related()`` are executed after the
``QuerySet`` has begun to be evaluated and the primary query has been executed.
If you have an iterable of model instances, you can prefetch related attributes
on those instances using the :func:`~django.db.models.prefetch_related_objects`
function.
Note that the result cache of the primary ``QuerySet`` and all specified related
objects will then be fully loaded into memory. This changes the typical
behavior of ``QuerySets``, which normally try to avoid loading all objects into
@ -2998,8 +3002,8 @@ by the aggregate.
.. _SQLite documentation: https://www.sqlite.org/contrib
Query-related classes
=====================
Query-related tools
===================
This section provides reference material for query-related tools not documented
elsewhere.
@ -3064,3 +3068,21 @@ attribute:
provide a significant speed improvement over traditional
``prefetch_related`` calls which store the cached result within a
``QuerySet`` instance.
``prefetch_related_objects()``
------------------------------
.. function:: prefetch_related_objects(model_instances, *related_lookups)
.. versionadded:: 1.10
Prefetches the given lookups on an iterable of model instances. This is useful
in code that receives a list of model instances as opposed to a ``QuerySet``;
for example, when fetching models from a cache or instantiating them manually.
Pass an iterable of model instances (must all be of the same class) and the
lookups or :class:`Prefetch` objects you want to prefetch for. For example::
>>> from django.db.models import prefetch_related_objects
>>> restaurants = fetch_top_restaurants_from_cache() # A list of Restaurants
>>> prefetch_related_objects(restaurants, 'pizzas__toppings')