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

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()
@@ -15,24 +16,28 @@ class Article(models.Model):
     article_text = models.TextField()
 
     class Meta:
-        ordering = ('pub_date','headline')
+        ordering = ('pub_date', 'headline')
         # A utf-8 verbose name (Ångström's Articles) to test they are valid.
         verbose_name = "\xc3\x85ngstr\xc3\xb6m's Articles"
 
     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')