protected function getSortableClass($column_key)
    {
        $classes = NULL;

        if ($this->getColumnOption($column_key, self::COLUMN_OPTION_SORTABLE))
        {
            $classes .= 'sorting ';
            if (array_key_exists($column_key, $this->columnOrders))
            {
                $order_method = $this->columnOrders[$column_key];
                switch ($order_method)
                {
                    case 'desc':
                        $classes .= 'sorting_asc ';
                        break;
                    default:
                        $classes .= 'sorting_desc ';
                }
            }
        }

        return $classes;
    }
protected function getSortableClass($column_key)
    {
        $classes = NULL;

        if ($this->getColumnOption($column_key, self::COLUMN_OPTION_SORTABLE))
        {
            $classes .= 'sorting ';
            if (array_key_exists($column_key, $this->columnOrders))
            {
                $order_method = $this->columnOrders[$column_key];
                switch ($order_method)
                {
                    case 'desc':
                        $classes .= 'sorting_asc ';
                        break;
                    default:
                        $classes .= 'sorting_desc ';
                }
            }
        }

        return $classes;
    }
protected function getSortableClass ( $ column_key ) { $ classes = NULL ; if ( $ this -> getColumnOption ( $ column_key , self :: COLUMN_OPTION_SORTABLE ) ) { $ classes .= 'sorting ' ; if ( array_key_exists ( $ column_key , $ this -> columnOrders ) ) { $ order_method = $ this -> columnOrders [ $ column_key ] ; switch ( $ order_method ) { case 'desc' : $ classes .= 'sorting_asc ' ; break ; default : $ classes .= 'sorting_desc ' ; } } } return $ classes ; }
Get column sortable class

@param   string  $column_key
@return null|string
Get column sortable class