Add support for HEAD requests of resources

Brian Curtin · Brian Curtin · commit ab8308a0ccc1 · 2014-07-01T14:20:44.000-05:00
Allow Resource.head* to make HEAD requests. When header data comes back,
X-Trans-Id headers are converted into 'id' data to match the rest of
the response types, and to match Resource.id attribute access.

Change-Id: I6d898f0734bbdbcb02b79d3387ee8248e401a36e
diff --git a/openstack/resource.py b/openstack/resource.py
@@ -252,6 +252,30 @@ def get(self, session):
         self._attrs.update(body)
         self._loaded = True
 
+    @classmethod
+    def head_data_by_id(cls, session, r_id):
+        if not cls.allow_retrieve:
+            raise exceptions.MethodNotSupported('retrieve')
+
+        url = utils.urljoin(cls.base_path, r_id)
+
+        data = session.head(url, service=cls.service, accept=None).headers
+        resp_id = data.pop("X-Trans-Id", None)
+        if resp_id:
+            data["id"] = resp_id
+
+        return data
+
+    @classmethod
+    def head_by_id(cls, session, r_id):
+        data = cls.head_data_by_id(session, r_id)
+        return cls.existing(**data)
+
+    def head(self, session):
+        data = self.head_data_by_id(session, self.id)
+        self._attrs.update(data)
+        self._loaded = True
+
     @classmethod
     def update_by_id(cls, session, r_id, attrs):
         if not cls.allow_update:
diff --git a/openstack/tests/test_resource.py b/openstack/tests/test_resource.py
@@ -99,6 +99,24 @@ def test_get(self):
         self.assertEqual(fake_attr1, obj.first)
         self.assertEqual(fake_attr2, obj.second)
 
+    @httpretty.activate
+    def test_head(self):
+        self.stub_url(httpretty.HEAD, path=[fake_path, fake_id],
+                      name=fake_name,
+                      attr1=fake_attr1,
+                      attr2=fake_attr2,
+                      x_trans_id=fake_id)
+        obj = FakeResource.head_by_id(self.session, fake_id)
+
+        self.assertEqual(fake_id, int(obj.id))
+        self.assertEqual(fake_name, obj['name'])
+        self.assertEqual(fake_attr1, obj['attr1'])
+        self.assertEqual(fake_attr2, obj['attr2'])
+
+        self.assertEqual(fake_name, obj.name)
+        self.assertEqual(fake_attr1, obj.first)
+        self.assertEqual(fake_attr2, obj.second)
+
     @httpretty.activate
     def test_update(self):
         new_attr1 = 'attr5'
