Don't use session at all for content rules, set the event in the request to be able to access comment attributes. This fixes 'InvalidObjectReference: A new object is reachable from multiple databases.' if comment contains a RichTextValue which contains a RawValueHolder (persistent object).

plone/app/discussion/contentrules.py

@@ -28,22 +28,18 @@ class CommentSubstitution(BaseSubstitution):
     """
     def __init__(self, context, **kwargs):
         super(CommentSubstitution, self).__init__(context, **kwargs)
-        self._session = None
 
     @property
-    def session(self):
+    def event(self):
-        """ User session
+        """ event that triggered the content rule
         """
-        if self._session is None:
+        return self.context.REQUEST.get('event')
-            sdm = getattr(self.context, 'session_data_manager', None)
-            self._session = sdm.getSessionData(create=False) if sdm else {}
-        return self._session
 
     @property
     def comment(self):
         """ Get changed inline comment
         """
-        return self.session.get('comment', {})
+        return self.event.comment
 
 class Id(CommentSubstitution):
     """ Comment id string substitution
@@ -54,7 +50,7 @@ class Id(CommentSubstitution):
     def safe_call(self):
         """ Safe call
         """
-        return self.comment.get('comment_id', u'')
+        return getattr(self.comment, 'comment_id', u'')
 
 class Text(CommentSubstitution):
     """ Comment text
@@ -65,7 +61,7 @@ class Text(CommentSubstitution):
     def safe_call(self):
         """ Safe call
         """
-        return self.comment.get('text', u'')
+        return getattr(self.comment, 'text', u'')
 
 class AuthorUserName(CommentSubstitution):
     """ Comment author user name string substitution
@@ -76,7 +72,7 @@ class AuthorUserName(CommentSubstitution):
     def safe_call(self):
         """ Safe call
         """
-        return self.comment.get('author_username', u'')
+        return getattr(self.comment, 'author_username', u'')
 
 class AuthorFullName(CommentSubstitution):
     """ Comment author full name string substitution
@@ -87,7 +83,7 @@ class AuthorFullName(CommentSubstitution):
     def safe_call(self):
         """ Safe call
         """
-        return self.comment.get('author_name', u'')
+        return getattr(self.comment, 'author_name', u'')
 
 class AuthorEmail(CommentSubstitution):
     """ Comment author email string substitution
@@ -98,4 +94,4 @@ class AuthorEmail(CommentSubstitution):
     def safe_call(self):
         """ Safe call
         """
-        return self.comment.get('author_email', u'')
+        return getattr(self.comment, 'author_email', u'')

plone/app/discussion/events.py

@@ -19,16 +19,10 @@ class DiscussionEvent(object):
         for key, value in kwargs.items():
             setattr(self, key, value)
 
-        # Add comment on session to easily define content-rules dynamic strings
+        # Add event to the request to be able to access comment attributes
-        sdm = getattr(context, 'session_data_manager', None)
+        # in content-rules dynamic strings
-        session = sdm.getSessionData(create=True) if sdm else None
+        request = context.REQUEST
-
+        request.set('event', self)
-        if session:
-            sessionComment = dict(
-                (field, getattr(comment, field, None)) for field in IComment
-                if not field.startswith('_')
-            )
-            session.set('comment', sessionComment)
 
 class CommentAddedEvent(DiscussionEvent):
     """ Event to be triggered when a Comment is added

plone/app/discussion/tests/test_contentrules.py

@@ -1,9 +1,7 @@
 # -*- coding: utf-8 -*-
 
 import unittest2 as unittest
-from Testing import ZopeTestCase as ztc
 from zope.component import createObject, getAdapter
-from zope.event import notify
 from plone.app.testing import TEST_USER_ID, setRoles
 
 from plone.contentrules.rule.interfaces import IRuleEventType
@@ -25,9 +23,6 @@ class CommentContentRulesTest(unittest.TestCase):
     layer = PLONE_APP_DISCUSSION_INTEGRATION_TESTING
 
     def setUp(self):
-        # Setup session manager
-        ztc.utils.setupCoreSessions(self.layer['app'])
-
         # Setup sandbox
         self.portal = self.layer['portal']
         self.request = self.layer['request']
@@ -94,9 +89,6 @@ class ReplyContentRulesTest(unittest.TestCase):
     layer = PLONE_APP_DISCUSSION_INTEGRATION_TESTING
 
     def setUp(self):
-        # Setup session manager
-        ztc.utils.setupCoreSessions(self.layer['app'])
-
         # Setup sandbox
         self.portal = self.layer['portal']
         self.request = self.layer['request']