fix-#725: queryset delete() should return the number of deleted objects

mongoengine/queryset/base.py

@@ -405,6 +405,7 @@ class BaseQuerySet(object):
             will force an fsync on the primary server.
         :param _from_doc_delete: True when called from document delete therefore
             signals will have been triggered so don't loop.
+        :returns number of deleted documents
         """
         queryset = self.clone()
         doc = queryset._document
@@ -422,9 +423,11 @@ class BaseQuerySet(object):
                                 has_delete_signal) and not _from_doc_delete
 
         if call_document_delete:
+            cnt = 0
             for doc in queryset:
                 doc.delete(write_concern=write_concern)
-            return
+                cnt += 1
+            return cnt
 
         delete_rules = doc._meta.get('delete_rules') or {}
         # Check for DENY rules before actually deleting/nullifying any other
@@ -455,8 +458,8 @@ class BaseQuerySet(object):
                     write_concern=write_concern,
                     **{'pull_all__%s' % field_name: self})
 
-        queryset._collection.remove(
-            queryset._query, write_concern=write_concern)
+        result = queryset._collection.remove(queryset._query, write_concern=write_concern)
+        return result["n"]
 
     def update(self, upsert=False, multi=True, write_concern=None,
                full_result=False, **update):

tests/queryset/queryset.py

@@ -4390,6 +4390,17 @@ class QuerySetTest(unittest.TestCase):
             {'_id': None, 'avg': 29, 'total': 2}
         ])
 
+    def test_delete_count(self):
+        [self.Person(name="User {0}".format(i), age=i * 10).save() for i in xrange(1, 4)]
+        self.assertEqual(self.Person.objects().delete(), 3)  # test ordinary QuerySey delete count
+
+        [self.Person(name="User {0}".format(i), age=i * 10).save() for i in xrange(1, 4)]
+
+        self.assertEqual(self.Person.objects().skip(1).delete(), 2)  # test Document delete with existing documents
+
+        self.Person.objects().delete()
+        self.assertEqual(self.Person.objects().skip(1).delete(), 0)  # test Document delete without existing documents
+
 
 if __name__ == '__main__':
     unittest.main()