protected function validateSortableParameters($key, $direction)
    {
        if (is_null($key))
        {
            // We are using the facade here instead of the request helper
            // to make this package compatible with Laravel 5.0
            $key = \Request::input(Supporter::keyName);
        }

        if (is_null($direction))
        {
            $direction = \Request::input(Supporter::directionName);
        }

        $direction = $this->getSortableDirection($direction);
        $key = $this->getSortableKey($key);

        $this->setSupporterParams($key, $direction);

        return array($key, $direction);
    }