[IMP] mail: added message_last_update field. This field is a datetime

field, updated everytime message_post in called. This allows to build filters, search or
actions based on the last message date, for reporting for example.

bzr revid: tde@openerp.com-20140206094831-nvyds6nqz0v25t59

addons/mail/mail_thread.py

@@ -296,6 +296,9 @@ class mail_thread(osv.AbstractModel):
             auto_join=True,
             string='Messages',
             help="Messages and communication history"),
+        'message_last_update': fields.datetime('Last Message Date',
+            help='Date of the last message posted on the record. Only messages going'
+                 'through the message_post API are taken into account for better performances.'),
         'message_unread': fields.function(_get_message_data,
             fnct_search=_search_message_unread, multi="_get_message_data",
             type='boolean', string='Unread Messages',
@@ -1522,8 +1525,13 @@ class mail_thread(osv.AbstractModel):
         for x in ('from', 'to', 'cc'):
             values.pop(x, None)
 
-        # Create and auto subscribe the author
+        # Post the message
         msg_id = mail_message.create(cr, uid, values, context=context)
+
+        # Post-process: subscribe author, update message_last_update
+        if model and model != 'mail.thread' and thread_id:
+            # done with SUPERUSER_ID, because on some models users can post only with read access, not necessarily write access
+            self.write(cr, SUPERUSER_ID, [thread_id], {'message_last_update': fields.datetime.now()}, context=context)
         message = mail_message.browse(cr, uid, msg_id, context=context)
         if message.author_id and thread_id and type != 'notification' and not context.get('mail_create_nosubscribe'):
             self.message_subscribe(cr, uid, [thread_id], [message.author_id.id], context=context)