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Fixed #10182 -- Corrected realiasing and the process of evaluating values() for queries with aggregate clauses. This means that aggregate queries can now be used as subqueries (such as in an __in clause). Thanks to omat for the report.

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This involves a slight change to the interaction of annotate() and values() clauses that specify a list of columns. See the docs for details.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@9888 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Russell Keith-Magee
2009-02-23 14:47:59 +00:00
parent 4bd24474c0
commit 542709d0d1
7 changed files with 102 additions and 32 deletions
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14
docs/topics/db/aggregation.txt
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@@ -284,9 +284,6 @@ two authors with the same name, their results will be merged into a single
result in the output of the query; the average will be computed as the
average over the books written by both authors.
The annotation name will be added to the fields returned
as part of the ``ValuesQuerySet``.
Order of ``annotate()`` and ``values()`` clauses
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -303,12 +300,21 @@ output.
For example, if we reverse the order of the ``values()`` and ``annotate()``
clause from our previous example::
>>> Author.objects.annotate(average_rating=Avg('book__rating')).values('name')
>>> Author.objects.annotate(average_rating=Avg('book__rating')).values('name', 'average_rating')
This will now yield one unique result for each author; however, only
the author's name and the ``average_rating`` annotation will be returned
in the output data.
You should also note that ``average_rating`` has been explicitly included
in the list of values to be returned. This is required because of the
ordering of the ``values()`` and ``annotate()`` clause.
If the ``values()`` clause precedes the ``annotate()`` clause, any annotations
will be automatically added to the result set. However, if the ``values()``
clause is applied after the ``annotate()`` clause, you need to explicitly
include the aggregate column.
Aggregating annotations
-----------------------