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

1 files changed, 15 insertions, 0 deletions

diff --git a/docs/howto/custom-lookups.txt b/docs/howto/custom-lookups.txt
index 32037a29aa..55fdc42237 100644
--- a/docs/howto/custom-lookups.txt
+++ b/docs/howto/custom-lookups.txt
@@ -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``