[1.5.x] Fixed #21203 -- resolve_columns fields misalignment

In queries using .defer() together with .select_related() the values
and fields arguments didn't align properly for resolve_columns().

Backpatch of 8c27247397cf16b17d0153ae059593c5a468de01 from master.

3 files changed, 21 insertions, 4 deletions

diff --git a/django/db/models/sql/compiler.py b/django/db/models/sql/compiler.py
index 18741655d8..ab249e50a0 100644
--- a/django/db/models/sql/compiler.py
+++ b/django/db/models/sql/compiler.py
@@ -800,9 +800,8 @@ class SQLCompiler(object):
                         # into `resolve_columns` because it wasn't selected.
                         only_load = self.deferred_to_columns()
                         if only_load:
-                            db_table = self.query.model._meta.db_table
-                            fields = [f for f in fields if db_table in only_load and
-                                      f.column in only_load[db_table]]
+                            fields = [f for f in fields if f.model._meta.db_table not in only_load or
+                                      f.column in only_load[f.model._meta.db_table]]
                         if has_aggregate_select:
                             # pad None in to fields for aggregates
                             fields = fields[:aggregate_start] + [
diff --git a/tests/regressiontests/queries/models.py b/tests/regressiontests/queries/models.py
index 4ce696c277..143e620670 100644
--- a/tests/regressiontests/queries/models.py
+++ b/tests/regressiontests/queries/models.py
@@ -401,3 +401,12 @@ class ModelA(models.Model):
     name = models.TextField()
     b = models.ForeignKey(ModelB, null=True)
     d = models.ForeignKey(ModelD)
+
+class Ticket21203Parent(models.Model):
+    parentid = models.AutoField(primary_key=True)
+    parent_bool = models.BooleanField(default=True)
+    created = models.DateTimeField(auto_now=True)
+
+class Ticket21203Child(models.Model):
+    childid = models.AutoField(primary_key=True)
+    parent = models.ForeignKey(Ticket21203Parent)
diff --git a/tests/regressiontests/queries/tests.py b/tests/regressiontests/queries/tests.py
index 33e5337f58..c7e746e2d0 100644
--- a/tests/regressiontests/queries/tests.py
+++ b/tests/regressiontests/queries/tests.py
@@ -23,7 +23,8 @@ from .models import (Annotation, Article, Author, Celebrity, Child, Cover,
     Ranking, Related, Report, ReservedName, Tag, TvChef, Valid, X, Food, Eaten,
     Node, ObjectA, ObjectB, ObjectC, CategoryItem, SimpleCategory,
     SpecialCategory, OneToOneCategory, NullableName, ProxyCategory,
-    SingleObject, RelatedObject, ModelA, ModelD)
+    SingleObject, RelatedObject, ModelA, ModelD,
+    Ticket21203Parent, Ticket21203Child)
 
 
 class BaseQuerysetTest(TestCase):
@@ -2149,3 +2150,11 @@ class EmptyStringPromotionTests(TestCase):
             self.assertIn('LEFT OUTER JOIN', str(qs.query))
         else:
             self.assertNotIn('LEFT OUTER JOIN', str(qs.query))
+
+class Ticket21203Tests(TestCase):
+    def test_ticket_21203(self):
+        p = Ticket21203Parent.objects.create(parent_bool=True)
+        c = Ticket21203Child.objects.create(parent=p)
+        qs = Ticket21203Child.objects.select_related('parent').defer('parent__created')
+        self.assertQuerysetEqual(qs, [c], lambda x: x)
+        self.assertIs(qs[0].parent.parent_bool, True)