Logging all table changes to another table

Since the site is user-editable, it needs some way to log all changes to certain tables, so they can be undone, if hit by vandals adding bad data. What I came up with this: model classes that need this (not all do) inherit from Journalled (as well as SQLObject, of course). Journalled overrides the __setattr__ and set() methods, and creates entries in the UpdateLog table for each change.

class UpdateLog(SQLObject):
    created = DateTimeCol(default=datetime.now)
    changed_by = IntCol()
    table_name = UnicodeCol(length=12)
    table_id = IntCol()
    attrib_name = UnicodeCol(length=20)
    attrib_old_value = UnicodeCol()
    attrib_new_value = UnicodeCol()

    def _get_attrib_old_value(self):
        return pickle.loads(str(self._SO_get_attrib_old_value()))
    def _set_attrib_old_value(self, value):
        self._SO_set_attrib_old_value(pickle.dumps(value))
    def _get_attrib_new_value(self):
        return pickle.loads(str(self._SO_get_attrib_new_value()))
    def _set_attrib_new_value(self, value):
        self._SO_set_attrib_new_value(pickle.dumps(value))

The old and new values are stored as actual Python objects. IDs are stored as just Ints, no relationships, since entries here can come from more than one table.

# Classes inheriting from this will have changes stored in the UpdateLog table
class Journalled(object):

    def __setattr__(self, name, value):
        if name in self.sqlmeta.columns.keys():
            self._record_update({name:value})
        super(Journalled, self).__setattr__(name, value)

    def set(self, **kw):
        self._record_update(kw)
        super(Journalled, self).set(**kw)

    def _record_update(self, updates):
        for name, value in updates.iteritems():
            old_value = getattr(self, name, None)
            if old_value != value:
                try:
                    current_user = identity.current.user.id
                except:
                    current_user = None
                u = UpdateLog(
                    changed_by=current_user,
                    table_name=self.sqlmeta.table,
                    table_id=self.id,
                    attrib_name=name,
                    attrib_old_value=old_value,
                    attrib_new_value=value
                    )

Honestly, with this in place, I haven't actually written the code to roll back any vandalism. The data is all in the UpdateLog, so I can put it off until the website actually gets hit ;-)

SQLObject svn trunk also appears to have recently added table versioning support. Sounds good, but I haven't tried it yet.