protected function getTokenColumn($column)
    {
        if (! array_key_exists($column, $this->tokenColumns)) {
            // This should never happen. If it does, then it means
            // that someone is a moron and has removed required
            // settings from the config files. Better safe than sorry.
            throw new BadRequestHttpException;
        }

        return $this->tokenColumns[$column];
    }