Fix queue metadata update issue

Currently when updating queue's metadata, the default type of
those metadata values are string. But in Zaqar some of them are
integer. So this patch will convert those reserved metadata
before saving.

Closes-Bug: #1581253

Change-Id: I6e3a6b8f7dd96e1e475454fd7b721878adcb1bc8

zaqar_ui/api/zaqar.py

@@ -12,9 +12,9 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-
 from __future__ import absolute_import
 import logging
+import six
 from zaqarclient.queues import client as zaqar_client
 
 from horizon import exceptions
@@ -23,6 +23,8 @@ from openstack_dashboard.api import base
 
 LOG = logging.getLogger(__name__)
 
+RESERVED_QUEUE_METADATA = ["_max_messages_post_size", "_default_message_ttl"]
+
 
 @memoized
 def zaqarclient(request):
@@ -75,6 +77,10 @@ def queue_update(request, queue_name, metadata):
     # user can change ttl, max message size and metadata
 
     queue = zaqarclient(request).queue(queue_name, auto_create=False)
+    for key in RESERVED_QUEUE_METADATA:
+        if (key in metadata and isinstance(metadata[key], six.string_types)):
+            metadata[key] = int(metadata[key])
+
     queue.metadata(new_meta=metadata)
     return queue