Enhance exception translation to better handle NeutronExceptions

NeutronExceptions have a 'message' class attribute that holds the
generic error message template, e.g. "Network %(network)s not found",
unfortunately, because the names are the same, it was overshadowing the
actual exception instance 'message', e.g. "Network 1 not found", after
translation when the exception was serialized to JSON.

This patch puts the exception's actual message in a new field called
'msg' and overwrites NeutronException unicode() so that 'msg' is used
during serialization and we'll get the correct message on the REST API
response.

Fixes bug: #1212882

Change-Id: I3965bffb1c2c2eee0af440d1ecd30ccb3bb958d5

neutron/api/v2/resource.py

@@ -147,9 +147,12 @@ def translate(translatable, locale):
               was not translated
     """
     localize = gettextutils.get_localized_message
-    if isinstance(translatable, Exception):
+    if isinstance(translatable, exceptions.NeutronException):
+        translatable.msg = localize(translatable.msg, locale)
+    elif isinstance(translatable, webob.exc.HTTPError):
+        translatable.detail = localize(translatable.detail, locale)
+    elif isinstance(translatable, Exception):
         translatable.message = localize(translatable.message, locale)
-        if isinstance(translatable, webob.exc.HTTPError):
-            translatable.detail = localize(translatable.detail, locale)
-        return translatable
-    return localize(translatable, locale)
+    else:
+        return localize(translatable, locale)
+    return translatable

neutron/common/exceptions.py

@@ -34,13 +34,17 @@ class NeutronException(Exception):
     def __init__(self, **kwargs):
         try:
             super(NeutronException, self).__init__(self.message % kwargs)
+            self.msg = self.message % kwargs
         except Exception:
             if _FATAL_EXCEPTION_FORMAT_ERRORS:
                 raise
             else:
                 # at least get the core message out if something happened
                 super(NeutronException, self).__init__(self.message)
 
+    def __unicode__(self):
+        return unicode(self.msg)
+
 
 class BadRequest(NeutronException):
     message = _('Bad %(resource)s request: %(msg)s')

neutron/tests/unit/test_api_v2_resource.py

@@ -160,8 +160,7 @@ class TestException(q_exc.NeutronException):
         self.assertEqual(wsgi.XMLDeserializer().deserialize(res.body),
                          expected_res)
 
-    @mock.patch('neutron.openstack.common.gettextutils.Message.data',
-                new_callable=mock.PropertyMock)
+    @mock.patch('neutron.openstack.common.gettextutils.get_localized_message')
     def test_unmapped_neutron_error_localized(self, mock_translation):
         gettextutils.install('blaa', lazy=True)
         msg_translation = 'Translated error'
@@ -223,8 +222,7 @@ class TestException(q_exc.NeutronException):
         self.assertEqual(wsgi.XMLDeserializer().deserialize(res.body),
                          expected_res)
 
-    @mock.patch('neutron.openstack.common.gettextutils.Message.data',
-                new_callable=mock.PropertyMock)
+    @mock.patch('neutron.openstack.common.gettextutils.get_localized_message')
     def test_mapped_neutron_error_localized(self, mock_translation):
         gettextutils.install('blaa', lazy=True)
         msg_translation = 'Translated error'