From 5bbf8564e20241e0bd9c28aca32dd519b6d19085 Mon Sep 17 00:00:00 2001
From: adieu <adieu@adieu.me>
Date: Fri, 26 Dec 2014 16:38:50 +0800
Subject: [PATCH 1/2] Add `keys` function to `Query`.

---
 gcloud/datastore/query.py | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/gcloud/datastore/query.py b/gcloud/datastore/query.py
index 9ae6790daca8..e7611f11247b 100644
--- a/gcloud/datastore/query.py
+++ b/gcloud/datastore/query.py
@@ -516,6 +516,14 @@ def projection(self, projection=None):
             clone._pb.projection.add().property.name = projection_name
         return clone
 
+    def keys(self):
+        """Adds a projection to get keys only
+
+        :rtype: :class:`Query`
+        :returns: A new Query instance only returns entity keys
+        """
+        return self.projection(['__key__'])
+
     def offset(self, offset=None):
         """Adds offset to the query to allow pagination.
 

From 349af40e797b3ef728210daa715b1dbebe618f01 Mon Sep 17 00:00:00 2001
From: adieu <adieu@adieu.me>
Date: Wed, 31 Dec 2014 22:16:20 +0800
Subject: [PATCH 2/2] Add test for `Query.keys`.

---
 gcloud/datastore/test_query.py | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/gcloud/datastore/test_query.py b/gcloud/datastore/test_query.py
index e0b2f4702a5a..b952fdf7af0c 100644
--- a/gcloud/datastore/test_query.py
+++ b/gcloud/datastore/test_query.py
@@ -513,6 +513,15 @@ def test_projection_multiple_calls(self):
         after = before.projection(_PROJECTION2)
         self.assertEqual(after.projection(), _PROJECTION2)
 
+    def test_keys(self):
+        _KIND = 'KIND'
+        before = self._makeOne(_KIND)
+        after = before.keys()
+        projection_pb = list(after.to_protobuf().projection)
+        self.assertEqual(len(projection_pb), 1)
+        prop_pb = projection_pb[0]
+        self.assertEqual(prop_pb.property.name, '__key__')
+
     def test_set_offset(self):
         _KIND = 'KIND'
         _OFFSET = 42