Ticket #20528: 20528-test-edf93127bf2f9dc35b45cdea5d39a1b417ab1638.diff

tests/regressiontests/select_related_regress/models.py

@@ -94 +94 @@
 
     def __str__(self):
         return self.name
+
+class ChildA(models.Model):
+    parent = models.ForeignKey(Parent)
+
+@python_2_unicode_compatible
+class ChildB(models.Model):
+    name = models.CharField(max_length=10)
+    parent = models.ForeignKey(Parent, null=True)
+    child = models.ForeignKey(ChildA, null=True)
+
+    def __str__(self):
+        return self.name

tests/regressiontests/select_related_regress/tests.py

@@ -1 +1 @@
 from __future__ import absolute_import, unicode_literals
 
+from django.db import models
 from django.test import TestCase
 from django.utils import six
 
 from .models import (Building, Child, Device, Port, Item, Country, Connection,
     ClientStatus, State, Client, SpecialClient, TUser, Person, Student,
-    Organizer, Class, Enrollment)
+    Organizer, Class, Enrollment, Parent, ChildA, ChildB)
 
 
 class SelectRelatedRegressTests(TestCase):
@@ -162 +163 @@
             # The select_related join was promoted as there is already an
             # existing join.
             self.assertTrue('LEFT OUTER' in str(qs.query))
+
+    def test_ticket_20528(self):
+        """
+        Regression for #20528
+
+        Using Qs and select_related with a certain config of ForeignKeys
+        resulted in incorrect joins.
+        """
+        parent = Parent.objects.create(name="foo")
+        childA = ChildA.objects.create(parent=parent)
+        childB = ChildB.objects.create(child=childA, name="Bobby")
+        queryset = ChildB.objects.filter(
+            models.Q(parent=parent) | models.Q(child__parent=parent)
+        )
+        expected_queryset = ['<ChildB: Bobby>']
+        # this always works
+        self.assertQuerysetEqual(queryset, expected_queryset)
+
+        # this started failing after 3fef304ff237fe692459c1f5b840acf7886c50bb
+        queryset = queryset.select_related('parent')
+        import sys
+        sys.stderr.write(str(queryset.query))
+        self.assertQuerysetEqual(queryset, expected_queryset)