def get_db_prep_save(self, value, connection=None):
        """
        Returns field's value prepared for saving into a database.
        """
        ## convert to settings.TIME_ZONE
        if value is not None:
            if value.tzinfo is None:
                value = default_tz.localize(value)
            else:
                value = value.astimezone(default_tz)
        return super(LocalizedDateTimeField, self).get_db_prep_save(value, connection=connection)