Ticket #17876: load_fields-upd.diff

django/db/models/query.py

@@ -1266 +1266 @@
         return None
 
     if only_load:
-        load_fields = only_load.get(klass)
+        load_fields = only_load.get(klass) or set()
         # When we create the object, we will also be creating populating
         # all the parent classes, so traverse the parent classes looking
         # for fields that must be included on load.

tests/modeltests/defer/models.py

@@ -22 +22 @@
 
 class BigChild(Primary):
     other = models.CharField(max_length=50)
+
+class ChildProxy(Child):
+    class Meta:
+        proxy=True

tests/modeltests/defer/tests.py

@@ -3 +3 @@
 from django.db.models.query_utils import DeferredAttribute
 from django.test import TestCase
 
-from .models import Secondary, Primary, Child, BigChild
+from .models import Secondary, Primary, Child, BigChild, ChildProxy
 
 
 class DeferTests(TestCase):
@@ -145 +145 @@
         obj.name = "bb"
         obj.save()
 
+        # using select related and only should not result in Exception
+        for obj in ChildProxy.objects.all().select_related().only('id'):
+            continue