Fixes ordering with custom db field names

Closes #125

mongoengine/queryset.py

@@ -939,6 +939,10 @@ class QuerySet(object):
             if key[0] in ('-', '+'):
                 key = key[1:]
             key = key.replace('__', '.')
+            try:
+                key = QuerySet._translate_field_name(self._document, key)
+            except:
+                pass
             key_list.append((key, direction))
 
         self._ordering = key_list

tests/queryset.py

@@ -1746,6 +1746,20 @@ class QuerySetTest(unittest.TestCase):
         Comment.drop_collection()
         Post.drop_collection()
 
+    def test_order_works_with_custom_db_field_names(self):
+        class Number(Document):
+            n = IntField(db_field='number')
+
+        Number.drop_collection()
+
+        n2 = Number.objects.create(n=2)
+        n1 = Number.objects.create(n=1)
+
+        self.assertEqual(list(Number.objects), [n2,n1])
+        self.assertEqual(list(Number.objects.order_by('n')), [n1,n2])
+
+        Number.drop_collection()
+
 
 class QTest(unittest.TestCase):