Fixed #12851 -- Another attempt at fixing select_related() with inherited models, this time with only(). Thanks to phxx for the test case.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@13059 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/models/query.py

@@ -1154,7 +1154,17 @@ def get_cached_row(klass, row, index_start, using, max_depth=0, cur_depth=0,
         return None
 
     restricted = requested is not None
-    load_fields = only_load and only_load.get(klass) or None
+    if only_load:
+        load_fields = only_load.get(klass)
+        # 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.
+        for parent in klass._meta.get_parent_list():
+            fields = only_load.get(parent)
+            if fields:
+                load_fields.update(fields)
+    else:
+        load_fields = None
     if load_fields:
         # Handle deferred fields.
         skip = set()

django/db/models/sql/query.py

@@ -556,10 +556,10 @@ class Query(object):
             # models.
             workset = {}
             for model, values in seen.iteritems():
-                for field in model._meta.fields:
+                for field, m in model._meta.get_fields_with_model():
                     if field in values:
                         continue
-                    add_to_dict(workset, model, field)
+                    add_to_dict(workset, m or model, field)
             for model, values in must_include.iteritems():
                 # If we haven't included a model in workset, we don't add the
                 # corresponding must_include fields for that model, since an

tests/regressiontests/select_related_regress/models.py

@@ -197,4 +197,13 @@ u'Troy Buswell'
 >>> troy.state.name
 u'Western Australia'
 
+# Also works if you use only, rather than defer
+>>> troy = SpecialClient.objects.select_related('state').only('name').get(name='Troy Buswell')
+>>> troy.name
+u'Troy Buswell'
+>>> troy.value
+42
+>>> troy.state.name
+u'Western Australia'
+
 """}