Fixed #18432 -- Prevented the ForeignKey field from creating an invalid query when chained. Thanks, Jann Kleen.

django/db/models/fields/related.py

@@ -359,7 +359,7 @@ class ReverseSingleRelatedObjectDescriptor(object):
             else:
                 other_field = self.field.rel.get_related_field()
                 if other_field.rel:
-                    params = {'%s__pk' % self.field.rel.field_name: val}
+                    params = {'%s__%s' % (self.field.rel.field_name, other_field.rel.field_name): val}
                 else:
                     params = {'%s__exact' % self.field.rel.field_name: val}
                 qs = self.get_query_set(instance=instance)

tests/regressiontests/model_regress/models.py

@@ -7,6 +7,7 @@ CHOICES = (
     (2, 'second'),
 )
 
+
 class Article(models.Model):
     headline = models.CharField(max_length=100, default='Default headline')
     pub_date = models.DateTimeField()
@@ -22,17 +23,21 @@ class Article(models.Model):
     def __unicode__(self):
         return self.headline
 
+
 class Movie(models.Model):
     #5218: Test models with non-default primary keys / AutoFields
     movie_id = models.AutoField(primary_key=True)
     name = models.CharField(max_length=60)
 
+
 class Party(models.Model):
     when = models.DateField(null=True)
 
+
 class Event(models.Model):
     when = models.DateTimeField()
 
+
 class Department(models.Model):
     id = models.PositiveIntegerField(primary_key=True)
     name = models.CharField(max_length=200)
@@ -40,6 +45,7 @@ class Department(models.Model):
     def __unicode__(self):
         return self.name
 
+
 class Worker(models.Model):
     department = models.ForeignKey(Department)
     name = models.CharField(max_length=200)
@@ -47,6 +53,7 @@ class Worker(models.Model):
     def __unicode__(self):
         return self.name
 
+
 class BrokenUnicodeMethod(models.Model):
     name = models.CharField(max_length=7)
 
@@ -55,5 +62,19 @@ class BrokenUnicodeMethod(models.Model):
         # object).
         return 'Názov: %s' % self.name
 
+
 class NonAutoPK(models.Model):
     name = models.CharField(max_length=10, primary_key=True)
+
+
+#18432: Chained foreign keys with to_field produce incorrect query
+class Model1(models.Model):
+    pkey = models.IntegerField(unique=True, db_index=True)
+
+
+class Model2(models.Model):
+    model1 = models.ForeignKey(Model1, unique=True, to_field='pkey')
+
+
+class Model3(models.Model):
+    model2 = models.ForeignKey(Model2, unique=True, to_field='model1')

tests/regressiontests/model_regress/tests.py

@@ -8,8 +8,7 @@ from django.test import TestCase, skipUnlessDBFeature
 from django.utils import tzinfo
 
 from .models import (Worker, Article, Party, Event, Department,
-    BrokenUnicodeMethod, NonAutoPK)
-
+    BrokenUnicodeMethod, NonAutoPK, Model1, Model2, Model3)
 
 
 class ModelTests(TestCase):
@@ -164,6 +163,19 @@ class ModelTests(TestCase):
             1
         )
 
+    def test_chained_fks(self):
+        """
+        Regression for #18432: Chained foreign keys with to_field produce incorrect query
+        """
+
+        m1 = Model1.objects.create(pkey=1000)
+        m2 = Model2.objects.create(model1=m1)
+        m3 = Model3.objects.create(model2=m2)
+
+        # this is the actual test for #18432
+        m3 = Model3.objects.get(model2=1000)
+        m3.model2
+
 
 class ModelValidationTest(TestCase):
     def test_pk_validation(self):