Commit be9d6453 authored by Anssi Kääriäinen's avatar Anssi Kääriäinen Committed by Tim Graham
Browse files

Fixed #24766 -- Added join promotion for Case expressions

parent 8e86d9d3

django/db/models/query_utils.py

+6 −1
Original line number Diff line number Diff line
@@ -87,7 +87,12 @@ class Q(tree.Node): 
        return clone



    def resolve_expression(self, query=None, allow_joins=True, reuse=None, summarize=False, for_save=False):

        clause, _ = query._add_q(self, reuse, allow_joins=allow_joins)

        # We must promote any new joins to left outer joins so that when Q is

        # used as an expression, rows aren't filtered due to joins.

        joins_before = query.tables[:]

        clause, joins = query._add_q(self, reuse, allow_joins=allow_joins)

        joins_to_promote = [j for j in joins if j not in joins_before]

        query.promote_joins(joins_to_promote)

        return clause



    @classmethod

docs/releases/1.8.2.txt

+4 −0
Original line number Diff line number Diff line
@@ -13,3 +13,7 @@ Bugfixes 


* Fixed crash when reusing the same ``Case`` instance in a query

  (:ticket:`24752`).



* Corrected join promotion for ``Case`` expressions. For example, annotating a

  query with a  ``Case`` expression could unexpectedly filter out results

  (:ticket:`24766`).

tests/expressions_case/tests.py

+32 −0
Original line number Diff line number Diff line
@@ -1016,6 +1016,38 @@ class CaseExpressionTests(TestCase): 
            transform=attrgetter('integer', 'test')

        )



    def test_join_promotion(self):

        o = CaseTestModel.objects.create(integer=1, integer2=1, string='1')

        # Testing that:

        # 1. There isn't any object on the remote side of the fk_rel

        #    relation. If the query used inner joins, then the join to fk_rel

        #    would remove o from the results. So, in effect we are testing that

        #    we are promoting the fk_rel join to a left outer join here.

        # 2. The default value of 3 is generated for the case expression.

        self.assertQuerysetEqual(

            CaseTestModel.objects.filter(pk=o.pk).annotate(

                foo=Case(

                    When(fk_rel__pk=1, then=2),

                    default=3,

                    output_field=models.IntegerField()

                ),

            ),

            [(o, 3)],

            lambda x: (x, x.foo)

        )

        # Now 2 should be generated, as the fk_rel is null.

        self.assertQuerysetEqual(

            CaseTestModel.objects.filter(pk=o.pk).annotate(

                foo=Case(

                    When(fk_rel__isnull=True, then=2),

                    default=3,

                    output_field=models.IntegerField()

                ),

            ),

            [(o, 2)],

            lambda x: (x, x.foo)

        )





class CaseDocumentationExamples(TestCase):

    @classmethod