From 0007535a469c45bf0cc72a486c37b871a6f01c5a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Stefan=20W=C3=B3jcik?= <wojcikstefan@gmail.com>
Date: Sun, 4 Dec 2016 00:33:42 -0500
Subject: [PATCH] Add support for cursor.comment (#1420)

---
 mongoengine/queryset/base.py |  8 ++++++++
 tests/queryset/queryset.py   | 16 +++++++++++++++-
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/mongoengine/queryset/base.py b/mongoengine/queryset/base.py
index bc70b44a..5f748b50 100644
--- a/mongoengine/queryset/base.py
+++ b/mongoengine/queryset/base.py
@@ -933,6 +933,14 @@ class BaseQuerySet(object):
         queryset._ordering = queryset._get_order_by(keys)
         return queryset
 
+    def comment(self, text):
+        """Add a comment to the query.
+
+        See https://docs.mongodb.com/manual/reference/method/cursor.comment/#cursor.comment
+        for details.
+        """
+        return self._chainable_method("comment", text)
+
     def explain(self, format=False):
         """Return an explain plan record for the
         :class:`~mongoengine.queryset.QuerySet`\ 's cursor.
diff --git a/tests/queryset/queryset.py b/tests/queryset/queryset.py
index 072b9122..88ae18aa 100644
--- a/tests/queryset/queryset.py
+++ b/tests/queryset/queryset.py
@@ -339,7 +339,6 @@ class QuerySetTest(unittest.TestCase):
 
     def test_update_write_concern(self):
         """Test that passing write_concern works"""
-
         self.Person.drop_collection()
 
         write_concern = {"fsync": True}
@@ -2215,6 +2214,21 @@ class QuerySetTest(unittest.TestCase):
             a.author.name for a in Author.objects.order_by('-author__age')]
         self.assertEqual(names, ['User A', 'User B', 'User C'])
 
+    def test_comment(self):
+        """Make sure adding a comment to the query works."""
+        class User(Document):
+            age = IntField()
+
+        with db_ops_tracker() as q:
+            adult = (User.objects.filter(age__gte=18)
+                .comment('looking for an adult')
+                .first())
+            ops = q.get_ops()
+            self.assertEqual(len(ops), 1)
+            op = ops[0]
+            self.assertEqual(op['query']['$query'], {'age': {'$gte': 18}})
+            self.assertEqual(op['query']['$comment'], 'looking for an adult')
+
     def test_map_reduce(self):
         """Ensure map/reduce is both mapping and reducing.
         """