我将此代码用于自定义post类型calles公文包。现在我想在项目之间使用父子关系。例如，我有一个URL为www.domain的公文包项目。de/portfolio-item1

另一个公文包项目应该是公文包项目1的子项目，url应该是www.domain。de/portfolio-item1/portfolio-item2

我是一个php初学者，我不知道如何才能实现这一点。谁能帮帮我吗？

 // Portfolio Post Type

    add_action(\'init\',\'wpthesis_create_portfolio_init\');
    function wpthesis_create_portfolio_init()  {
        $labels = array    
    (        \'name\' => _x(\'Portfolio\', \'post type general name\'),
             \'singular_name\' => _x(\'item\', \'post type singular name\'),
             \'add_new\' => _x(\'Add New\', \'Portfolio Item\'), 
             \'add_new_item\' => __(\'Add New Portfolio Item\'), 
             \'edit_item\' => __(\'Edit Portfolio Item\'),  
            \'new_item\' => __(\'New Portfolio Item\'),
            \'view_item\' => __(\'View Portfolio Item\'),
            \'search_items\' => __(\'Search Portfolio\'), 
            \'not_found\' =>  __(\'No portfolio items found\'), 
            \'not_found_in_trash\' => __(\'No portfolio items found in Trash\'), 
            \'parent_item_colon\' => \'\'    
    ); 

       $support = array    
    (       
     \'title\', 
           \'editor\',
            \'author\',
            \'thumbnail\',
            \'custom-fields\',
            \'comments\',
            \'genesis-seo\', 
            \'genesis-layouts\',
            \'revisions\'    
    );    

    $args = array  
      (     
       \'labels\' => $labels,
            \'public\' => TRUE,
            \'rewrite\' => array(\'slug\'=>(\'produkte-leistungen\'),\'with_front\'=>false),
            \'capability_type\' => \'page\', 
           \'hierarchical\' => FALSE,
            \'query_var\' => true, 
           \'supports\' => $support,        \'taxonomies\' => array(\'portfolio-category\'),
            \'menu_position\' => 5 
       );    
     register_post_type(\'portfolio\',$args);

            register_taxonomy(
            \'portfolio-category\', 
            \'portfolio\',        

    array(            
    \'hierarchical\' => TRUE, 
               \'label\' => \'Categories\',
                \'query_var\' => TRUE,
                \'rewrite\' => FALSE,       
     )    
    );  
    }