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Re-added docs for QuerySet reverse() and all() methods, refs #9000 - thanks ramiro 

git-svn-id: http://code.djangoproject.com/svn/django/trunk@9005 bcc190cf-cafb-0310-a4f2-bffc1f526a37
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Simon Willison 2008-09-11 00:24:02 +00:00
parent 0cd7fbec56
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38
docs/ref/models/querysets.txt
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@ -7,9 +7,9 @@ QuerySet API reference
.. currentmodule:: django.db.models .. currentmodule:: django.db.models
This document describes the details of the ``QuerySet`` API. It builds on the This document describes the details of the ``QuerySet`` API. It builds on the
material presented in the :ref:`model <topics-db-models>` and `database query material presented in the :ref:`model <topics-db-models>` and :ref:`database
<topics-db-queries>` guides, so you'll probably want to read and understand query <topics-db-queries>` guides, so you'll probably want to read and
those documents before reading this one. understand those documents before reading this one.
Throughout this reference we'll use the :ref:`example weblog models Throughout this reference we'll use the :ref:`example weblog models
<queryset-model-example>` presented in the :ref:`database query guide <queryset-model-example>` presented in the :ref:`database query guide
@ -192,6 +192,26 @@ There's no way to specify whether ordering should be case sensitive. With
respect to case-sensitivity, Django will order results however your database respect to case-sensitivity, Django will order results however your database
backend normally orders them. backend normally orders them.
``reverse()``
~~~~~~~~~~~~~
.. versionadded:: 1.0
Use the ``reverse()`` method to reverse the order in which a queryset's
elements are returned. Calling ``reverse()`` a second time restores the
ordering back to the normal direction.
To retrieve the ''last'' five items in a queryset, you could do this::
my_queryset.reverse()[:5]
Note that this is not quite the same as slicing from the end of a sequence in
Python. The above example will return the last item first, then the
penultimate item and so on. If we had a Python sequence and looked at
``seq[-5:]``, we would see the fifth-last item first. Django doesn't support
that mode of access (slicing from the end), because it's not possible to do it
efficiently in SQL.
Also, note that ``reverse()`` should generally only be called on a Also, note that ``reverse()`` should generally only be called on a
``QuerySet`` which has a defined ordering (e.g., when querying against ``QuerySet`` which has a defined ordering (e.g., when querying against
a model which defines a default ordering, or when using a model which defines a default ordering, or when using
@ -200,7 +220,6 @@ a model which defines a default ordering, or when using
ordering was undefined prior to calling ``reverse()``, and will remain ordering was undefined prior to calling ``reverse()``, and will remain
undefined afterward). undefined afterward).
``distinct()`` ``distinct()``
~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~
@ -393,6 +412,17 @@ Examples::
>>> Entry.objects.none() >>> Entry.objects.none()
[] []
``all()``
~~~~~~~~~~
.. versionadded:: 1.0
Returns a ''copy'' of the current ``QuerySet`` (or ``QuerySet`` subclass you
pass in). This can be useful in some situations where you might want to pass
in either a model manager or a ``QuerySet`` and do further filtering on the
result. You can safely call ``all()`` on either object and then you'll
definitely have a ``QuerySet`` to work with.
.. _select-related: .. _select-related:
``select_related()`` ``select_related()``