diff options
Diffstat (limited to 'docs/ref')
| -rw-r--r-- | docs/ref/models/querysets.txt | 15 |
1 files changed, 12 insertions, 3 deletions
diff --git a/docs/ref/models/querysets.txt b/docs/ref/models/querysets.txt index 05f7d36aa6..339b5e18fe 100644 --- a/docs/ref/models/querysets.txt +++ b/docs/ref/models/querysets.txt @@ -502,14 +502,23 @@ A few subtleties that are worth mentioning: made after a ``values()`` call will have its extra selected fields ignored. +* Calling :meth:`only()` and :meth:`defer()` after ``values()`` doesn't make + sense, so doing so will raise a ``NotImplementedError``. + +.. versionadded:: 1.7 + + The last point above is new. Previously, calling :meth:`only()` and + :meth:`defer()` after ``values()`` was allowed, but it either crashed or + returned incorrect results. + A ``ValuesQuerySet`` is useful when you know you're only going to need values from a small number of the available fields and you won't need the functionality of a model instance object. It's more efficient to select only the fields you need to use. -Finally, note a ``ValuesQuerySet`` is a subclass of ``QuerySet``, so it has all -methods of ``QuerySet``. You can call ``filter()`` on it, or ``order_by()``, or -whatever. Yes, that means these two calls are identical:: +Finally, note that a ``ValuesQuerySet`` is a subclass of ``QuerySet`` and it +implements most of the same methods. You can call ``filter()`` on it, +``order_by()``, etc. That means that these two calls are identical:: Blog.objects.values().order_by('id') Blog.objects.order_by('id').values() |