def post_update(self, attr):
"""Trigger that is executed after an attribute update."""
super(Message, self).post_update(attr)
# Automatically keep the message hash up to date.
if attr.name == 'message':
value = attr.value()
# MD5 works only on bytes, not on unicode
if isinstance(value, unicode):
value = value.encode('utf-8')
self['hash'] = md5sum(value)
def hash(self, message):
"""Return a unique message id for `message'."""
# MD5 works on bytes, not on unicode
if isinstance(message, unicode):
message = message.encode('utf-8')
return md5sum(message)
