mirrors/django
1
0
Fork 0
mirror of https://github.com/django/django.git synced 2025-07-24 05:36:15 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 4

Refs #28010 -- Allowed reverse related fields in SELECT FOR UPDATE .. OF.

Browse source 
Thanks Adam Chidlow for polishing the patch.
This commit is contained in:
Ran Benita 2017-10-17 11:28:00 +08:00 • committed by Tim Graham
parent 56b364bacc
commit 03049fb8d9
5 changed files with 61 additions and 6 deletions
Download patch file Download diff file Expand all files Collapse all files

13
docs/ref/models/querysets.txt
View file

@ -1628,6 +1628,19 @@ specify the related objects you want to lock in ``select_for_update(of=(...))``
using the same fields syntax as :meth:`select_related`. Use the value ``'self'``
to refer to the queryset's model.
You can't use ``select_for_update()`` on nullable relations::
>>> Person.objects.select_related('hometown').select_for_update()
Traceback (most recent call last):
...
django.db.utils.NotSupportedError: FOR UPDATE cannot be applied to the nullable side of an outer join
To avoid that restriction, you can exclude null objects if you don't care about
them::
>>> Person.objects.select_related('hometown').select_for_update().exclude(hometown=None)
<QuerySet [<Person: ...)>, ...]>
Currently, the ``postgresql``, ``oracle``, and ``mysql`` database
backends support ``select_for_update()``. However, MySQL doesn't support the
``nowait``, ``skip_locked``, and ``of`` arguments.