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Diffstat (limited to 'docs/ref/models')
| -rw-r--r-- | docs/ref/models/querysets.txt | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/docs/ref/models/querysets.txt b/docs/ref/models/querysets.txt index b366ef33a1..18cc1c679e 100644 --- a/docs/ref/models/querysets.txt +++ b/docs/ref/models/querysets.txt @@ -1221,6 +1221,31 @@ that it will be at some point, then using ``some_query_set.exists()`` will do more overall work (an additional query) than simply using ``bool(some_query_set)``. +``update(**kwargs)`` +~~~~~~~~~~~~~~~~~~~~ + +.. method:: update(**kwargs) + +Performs an SQL update query for the specified fields, and returns +the number of rows affected. The ``update()`` method is applied instantly and +the only restriction on the :class:`QuerySet` that is updated is that it can +only update columns in the model's main table. Filtering based on related +fields is still possible. You cannot call ``update()`` on a +:class:`QuerySet` that has had a slice taken or can otherwise no longer be +filtered. + +For example, if you wanted to update all the entries in a particular blog +to use the same headline:: + + >>> 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') + +The ``update()`` method does a bulk update and does not call any ``save()`` +methods on your models, nor does it emit the ``pre_save`` or ``post_save`` +signals (which are a consequence of calling ``save()``). + .. _field-lookups: Field lookups |