Commit 3190abcd authored by Aymeric Augustin's avatar Aymeric Augustin
Browse files

Fixed #18153 -- Reverse OneToOne lookups on unsaved instances. 

Thanks David Hatch and Anssi Kääriäinen for their inputs.
parent c9b4e9ac

django/db/models/fields/related.py

+15 −6
Original line number Diff line number Diff line
@@ -261,7 +261,11 @@ class SingleRelatedObjectDescriptor(object): 
        try:

            rel_obj = getattr(instance, self.cache_name)

        except AttributeError:

            params = {'%s__pk' % self.related.field.name: instance._get_pk_val()}

            related_pk = instance._get_pk_val()

            if related_pk is None:

                rel_obj = None

            else:

                params = {'%s__pk' % self.related.field.name: related_pk}

                try:

                    rel_obj = self.get_query_set(instance=instance).get(**params)

                except self.related.model.DoesNotExist:
@@ -301,8 +305,13 @@ class SingleRelatedObjectDescriptor(object): 
                    raise ValueError('Cannot assign "%r": instance is on database "%s", value is on database "%s"' %

                                        (value, instance._state.db, value._state.db))



        related_pk = getattr(instance, self.related.field.rel.get_related_field().attname)

        if related_pk is None:

            raise ValueError('Cannot assign "%r": "%s" instance isn\'t saved in the database.' %

                                (value, self.related.opts.object_name))



        # Set the value of the related field to the value of the related object's related field

        setattr(value, self.related.field.attname, getattr(instance, self.related.field.rel.get_related_field().attname))

        setattr(value, self.related.field.attname, related_pk)



        # Since we already know what the related object is, seed the related

        # object caches now, too. This avoids another db hit if you get the

tests/regressiontests/one_to_one_regress/tests.py

+40 −0
Original line number Diff line number Diff line
@@ -202,3 +202,43 @@ class OneToOneRegressionTests(TestCase): 
        with self.assertNumQueries(0):

            with self.assertRaises(UndergroundBar.DoesNotExist):

                self.p1.undergroundbar



    def test_get_reverse_on_unsaved_object(self):

        """

        Regression for #18153 and #19089.



        Accessing the reverse relation on an unsaved object

        always raises an exception.

        """

        p = Place()



        # When there's no instance of the origin of the one-to-one

        with self.assertNumQueries(0):

            with self.assertRaises(UndergroundBar.DoesNotExist):

                p.undergroundbar



        UndergroundBar.objects.create()



        # When there's one instance of the origin

        # (p.undergroundbar used to return that instance)

        with self.assertNumQueries(0):

            with self.assertRaises(UndergroundBar.DoesNotExist):

                p.undergroundbar



        UndergroundBar.objects.create()



        # When there are several instances of the origin

        with self.assertNumQueries(0):

            with self.assertRaises(UndergroundBar.DoesNotExist):

                p.undergroundbar



    def test_set_reverse_on_unsaved_object(self):

        """

        Writing to the reverse relation on an unsaved object

        is impossible too.

        """

        p = Place()

        b = UndergroundBar.objects.create()

        with self.assertNumQueries(0):

            with self.assertRaises(ValueError):

                p.undergroundbar = b