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Fixed #24747 -- Allowed transforms in QuerySet.order_by() and distinct(*fields).

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Matthew Wilkes
2017-06-18 16:53:40 +01:00
committed by Tim Graham
parent bf26f66029
commit 2162f0983d
15 changed files with 260 additions and 38 deletions
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15
docs/howto/custom-lookups.txt
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@@ -138,6 +138,21 @@ SQL::
Note that in case there is no other lookup specified, Django interprets
``change__abs=27`` as ``change__abs__exact=27``.
This also allows the result to be used in ``ORDER BY`` and ``DISTINCT ON``
clauses. For example ``Experiment.objects.order_by('change__abs')`` generates::
SELECT ... ORDER BY ABS("experiments"."change") ASC
And on databases that support distinct on fields (such as PostgreSQL),
``Experiment.objects.distinct('change__abs')`` generates::
SELECT ... DISTINCT ON ABS("experiments"."change")
.. versionchanged:: 2.1
Ordering and distinct support as described in the last two paragraphs was
added.
When looking for which lookups are allowable after the ``Transform`` has been
applied, Django uses the ``output_field`` attribute. We didn't need to specify
this here as it didn't change, but supposing we were applying ``AbsoluteValue``