Merge "model proxy: Throw custom exception when model not cached"

dragonflow/common/exceptions.py

@@ -52,6 +52,10 @@ class DBKeyNotFound(DragonflowException):
     message = _('DB Key not found, key=%(key)s')
 
 
+class ReferencedObjectNotFound(DragonflowException):
+    message = _('Referenced object not found. proxy=%(proxy)s')
+
+
 class CommandError(DragonflowException):
     message = _("Non-existent fields are specified: %(non_existent_fields)s")
 

dragonflow/db/model_proxy.py

@@ -12,10 +12,16 @@
 import copy
 import six
 
+from oslo_log import log
+
 from dragonflow._i18n import _
+from dragonflow.common import exceptions
 from dragonflow.db import db_store
 
 
+LOG = log.getLogger(__name__)
+
+
 class _ModelProxyBase(object):
     '''Base for proxy objects
 
@@ -74,8 +80,12 @@ class _ModelProxyBase(object):
         return not self == other
 
     def __getattr__(self, name):
-        if name != '_obj':
-            return getattr(self.get_object(), name)
+        if name == '_obj':
+            return
+        obj = self.get_object()
+        if obj is None:
+            raise exceptions.ReferencedObjectNotFound(proxy=self)
+        return getattr(obj, name)
 
     def __copy__(self):
         return self.__class__(self._id)

dragonflow/tests/unit/test_model_proxy.py

@@ -10,10 +10,12 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 import copy
+import testtools
 
 from jsonmodels import fields
 import mock
 
+from dragonflow.common import exceptions
 from dragonflow.db import db_store
 import dragonflow.db.field_types as df_fields
 import dragonflow.db.model_framework as mf
@@ -179,3 +181,9 @@ class TestObjectProxy(tests_base.BaseTestCase):
         self.assertEqual(model_test_ref, model_test_ref_deepcopy)
         self.assertNotEqual(id(model_test_ref), id(model_test_ref_copy))
         self.assertNotEqual(id(model_test_ref), id(model_test_ref_deepcopy))
+
+    def test_non_existing_reference(self):
+        reffing_model = RefferingModel(id='2', model_test='1')
+        self.db_store.get_one.return_value = None
+        with testtools.ExpectedException(exceptions.ReferencedObjectNotFound):
+            topic = reffing_model.model_test.topic  # noqa