[soc2009/multidb] Fixed #12402 -- QuerySet.defer now interacts properly with SQLCompiler subclasses that implement resolve_columns.

git-svn-id: http://code.djangoproject.com/svn/django/branches/soc2009/multidb@11911 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/models/sql/compiler.py

@@ -627,6 +627,13 @@ class SQLCompiler(object):
                             fields = self.query.select_fields + self.query.related_select_fields
                         else:
                             fields = self.query.model._meta.fields
+                        # If the field was deferred, exclude it from being passed
+                        # 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]]
                     row = self.resolve_columns(row, fields)
 
                 if self.query.aggregate_select:

tests/regressiontests/defer_regress/models.py

@@ -31,6 +31,10 @@ class Leaf(models.Model):
     def __unicode__(self):
         return self.name
 
+class ResolveThis(models.Model):
+    num = models.FloatField()
+    name = models.CharField(max_length=16)
+
 __test__ = {"regression_tests": """
 Deferred fields should really be deferred and not accidentally use the field's
 default value just because they aren't passed to __init__.

tests/regressiontests/defer_regress/tests.py

@@ -0,0 +1,9 @@
+from django.test import TestCase
+from models import ResolveThis
+
+class DeferRegressionTest(TestCase):
+    def test_resolve_columns(self):
+        rt = ResolveThis.objects.create(num=5.0, name='Foobar')
+        qs = ResolveThis.objects.defer('num')
+        self.assertEqual(1, qs.count())
+        self.assertEqual('Foobar', qs[0].name)