Fixed order-then-filter issue

mongoengine/queryset.py

@@ -431,7 +431,9 @@ class QuerySet(object):
                 self._cursor_obj.where(self._where_clause)
 
             # apply default ordering
-            if self._document._meta['ordering']:
+            if self._ordering:
+                self._cursor_obj.sort(self._ordering)
+            elif self._document._meta['ordering']:
                 self.order_by(*self._document._meta['ordering'])
 
             if self._limit is not None:

tests/queryset.py

@@ -1395,6 +1395,24 @@ class QuerySetTest(unittest.TestCase):
 
         Post.drop_collection()
 
+    def test_order_then_filter(self):
+        """Ensure that ordering still works after filtering.
+        """
+        class Number(Document):
+            n = IntField()
+
+        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])
+        self.assertEqual(list(Number.objects.order_by('n').filter()), [n1, n2])
+
+        Number.drop_collection()
+
+
 class QTest(unittest.TestCase):
 
     def test_empty_q(self):