Ticket #7530: django_related_null_fields_fix.patch

django/db/models/query.py

@@ -752 +752 @@
 
     restricted = requested is not None
     index_end = index_start + len(klass._meta.fields)
-    obj = klass(*row[index_start:index_end])
+    fields = row[index_start:index_end]
+    if not [x for x in fields if x is not None]:
+        # some select_related() queries return a list of None objects
+        return None, index_end
+    obj = klass(*fields)
     for f in klass._meta.fields:
         if (not f.rel or (not restricted and f.null) or
                 (restricted and f.name not in requested) or f.rel.parent_link):

tests/regressiontests/null_fk/models.py

@@ -47 +47 @@
 None
 
 >>> comments = Comment.objects.select_related('post__forum__system_info').all()
->>> [(c.id, c.post.id) for c in comments]
-[(1, 1), (2, None)]
->>> [(c.comment_text, c.post.title) for c in comments]
-[(u'My first comment', u'First Post'), (u'My second comment', None)]
+>>> [(c.id, c.comment_text, c.post) for c in comments]
+[(1, u'My first comment', <Post: First Post>), (2, u'My second comment', None)]
 
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