def __unicode__(self):
        format = {'ctype': self.content_type, 'cobj': self.content_object, 'site': self.site}
        if self.url:
            format['url'] = self.url
            string = '%(ctype)s "%(cobj)s" on http://%(site)s/%(url)s/'
        else:
            string = '%(ctype)s "%(cobj)s" on http://%(site)s/'
        return smart_unicode(string % format)