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Fixed #25871 -- Added expressions support to QuerySet.values().

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Ian Foote 2016-08-15 11:35:12 +10:00 • committed by Tim Graham
parent d4eefc7e2a
commit 39f35d4b9d
4 changed files with 115 additions and 7 deletions
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34
docs/ref/models/querysets.txt
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@ -506,7 +506,7 @@ Examples (those after the first will only work on PostgreSQL)::
``values()``
~~~~~~~~~~~~
.. method:: values(*fields)
.. method:: values(*fields, **expressions)
Returns a ``QuerySet`` that returns dictionaries, rather than model instances,
when used as an iterable.
@ -538,6 +538,23 @@ Example::
>>> Blog.objects.values('id', 'name')
<QuerySet [{'id': 1, 'name': 'Beatles Blog'}]>
The ``values()`` method also takes optional keyword arguments,
``**expressions``, which are passed through to :meth:`annotate`::
>>> from django.db.models.functions import Lower
>>> Blog.objects.values(lower_name=Lower('name'))
<QuerySet [{'lower_name': 'beatles blog'}]>
An aggregate within a ``values()`` clause is applied before other arguments
within the same ``values()`` clause. If you need to group by another value,
add it to an earlier ``values()`` clause instead. For example::
>>> from django.db.models import Count
>>> Blog.objects.values('author', entries=Count('entry'))
<QuerySet [{'author': 1, 'entries': 20}, {'author': 1, 'entries': 13}]>
>>> Blog.objects.values('author').annotate(entries=Count('entry'))
<QuerySet [{'author': 1, 'entries': 33}]>
A few subtleties that are worth mentioning:
* If you have a field called ``foo`` that is a
@ -603,6 +620,10 @@ You can also refer to fields on related models with reverse relations through
pronounced if you include multiple such fields in your ``values()`` query,
in which case all possible combinations will be returned.
.. versionchanged:: 1.11
Support for ``**expressions`` was added.
``values_list()``
~~~~~~~~~~~~~~~~~
@ -610,11 +631,14 @@ You can also refer to fields on related models with reverse relations through
This is similar to ``values()`` except that instead of returning dictionaries,
it returns tuples when iterated over. Each tuple contains the value from the
respective field passed into the ``values_list()`` call — so the first item is
the first field, etc. For example::
respective field or expression passed into the ``values_list()`` call — so the
first item is the first field, etc. For example::
>>> Entry.objects.values_list('id', 'headline')
[(1, 'First entry'), ...]
>>> from django.db.models.functions import Lower
>>> Entry.objects.values_list('id', Lower('headline'))
[(1, 'first entry'), ...]
If you only pass in a single field, you can also pass in the ``flat``
parameter. If ``True``, this will mean the returned results are single values,
@ -661,6 +685,10 @@ not having any author::
>>> Entry.objects.values_list('authors')
[('Noam Chomsky',), ('George Orwell',), (None,)]
.. versionchanged:: 1.11
Support for expressions in ``*fields`` was added.
``dates()``
~~~~~~~~~~~