innov
/
django1
1
0
Fork 0
Code Issues Pull Requests 1 Projects Releases Wiki Activity

Fixed #12859 -- Clarified the documentation on using multiple tables with .update() calls. Thanks to dwillis for the report. 

git-svn-id: http://code.djangoproject.com/svn/django/trunk@12515 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Russell Keith-Magee 2010-02-23 13:20:27 +00:00
parent 745b89f6e1
commit c306b78150
1 changed files with 8 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
docs/topics/db/queries.txt
View File

@ -778,7 +778,7 @@ a ``QuerySet``. You can do this with the ``update()`` method. For example::
You can only set non-relation fields and ``ForeignKey`` fields using this You can only set non-relation fields and ``ForeignKey`` fields using this
method. To update a non-relation field, provide the new value as a constant. method. To update a non-relation field, provide the new value as a constant.
To update ``ForeignKey`` fields, set the new value to be the new model To update ``ForeignKey`` fields, set the new value to be the new model
instance you want to point to. Example:: instance you want to point to. For example::
>>> b = Blog.objects.get(pk=1) >>> b = Blog.objects.get(pk=1)
@ -788,8 +788,13 @@ instance you want to point to. Example::
The ``update()`` method is applied instantly and returns the number of rows The ``update()`` method is applied instantly and returns the number of rows
affected by the query. The only restriction on the ``QuerySet`` that is affected by the query. The only restriction on the ``QuerySet`` that is
updated is that it can only access one database table, the model's main updated is that it can only access one database table, the model's main
table. So don't try to filter based on related fields or anything like that; table. You can filter based on related fields, but you can only update columns
it won't work. in the model's main table. Example::
>>> b = Blog.objects.get(pk=1)
# Update all the headlines belonging to this Blog.
>>> Entry.objects.select_related().filter(blog=b).update(headline='Everything is the same')
Be aware that the ``update()`` method is converted directly to an SQL Be aware that the ``update()`` method is converted directly to an SQL
statement. It is a bulk operation for direct updates. It doesn't run any statement. It is a bulk operation for direct updates. It doesn't run any