Fix missing 'transition' attribute in deserialized Response objects

Author: elioschmutz

changes/TI-3124.bugfix

@@ -0,0 +1 @@
+Fix generating task listing pdf for resolved dossiers in nightly jobs. [elioschmutz]

opengever/base/response.py

@@ -184,6 +184,20 @@ def __init__(self, response_type='default'):
         self.modified = None
         self.modifier = None
 
+    def __setstate__(self, state):
+        # Ensure backward compatibility with older serialized Response objects.
+        # Older pickled states may lack the 'transition' attribute, which leads to
+        # AttributeError when accessing the transition attribute.
+        #
+        # We do not define the transition-property in the IResponse-interface
+        # nor in the __init__ method, as it is only relevant for rare edge
+        # cases were we're working with old Response.
+        #
+        # Fixes: https://4teamwork.atlassian.net/browse/TI-3124
+        state['transition'] = state.get('transition', u'')
+
+        super(Response, self).__setstate__(state)
+
     def add_change(self, field_id, before, after, field_title=''):
         self.changes.append(PersistentDict(
             field_id=field_id,

opengever/task/tests/test_response.py

@@ -1,11 +1,14 @@
 from ftw.testbrowser import browsing
 from ftw.testbrowser.pages.statusmessages import info_messages
+from opengever.base.response import COMMENT_REMOVED_RESPONSE_TYPE
 from opengever.base.response import IResponseContainer
+from opengever.base.response import Response
 from opengever.testing import IntegrationTestCase
 from persistent import Persistent
 from persistent.list import PersistentList
 from persistent.mapping import PersistentMapping
 from plone import api
+import pickle
 
 
 class TestTaskResponses(IntegrationTestCase):
@@ -26,6 +29,22 @@ def test_response_and_response_changes_are_persistent(self, browser):
         self.assertIsInstance(response.changes, PersistentList)
         self.assertIsInstance(response.changes[0], PersistentMapping)
 
+    def test_old_responses_in_task_history_provides_the_transition_property(self):
+        """Tasks should only have TaskResponse objects in the response history.
+        But we've never migrated old response objects.
+
+        Because it'd be too much work to migrate all old Response objects to
+        TaskResponse objects, we ensure here that old Response objects at least
+        provide the 'transition' property after unpickling.
+        """
+        response = Response(response_type=COMMENT_REMOVED_RESPONSE_TYPE)
+
+        self.assertFalse(hasattr(response, 'transition'))
+
+        unpickled_response = pickle.loads(pickle.dumps(response))
+        self.assertTrue(hasattr(unpickled_response, 'transition'))
+        self.assertEqual(unpickled_response.transition, u'')
+
 
 class TestTaskResponseForm(IntegrationTestCase):