php – 调用未定义的函数convert_to_screen()

我正在开发一个插件,我必须扩展类WP_List_Table.我已经在我的插件文件中扩展了类(我不知道这是否是正确的方法？)并包含WP_List_Table,如下所示：

if(!class_exists('WP_List_Table')){
   require_once( ABSPATH . 'wp-admin/includes/class-wp-list-table.PHP' );
}

然后是扩展类的代码,然后我创建了一个我的表类的实例,如下所示：

<?PHP

 if ( ! class_exists( 'WP_List_Table' ) ) {
                require_once( ABSPATH . 'wp-admin/includes/class-wp-list-table.PHP' );
}


 Class Wp_Ban_User extends WP_List_Table
 {

    public function __construct()
    {
             add_action('admin_menu',array($this,'WBU_adminMenu'));
             parent::__construct( array(
                  'singular'=> 'wp_list_text_link', //Singular label
                  'plural' => 'wp_list_test_links', //plural label, also this well be one of the table css class
                  'ajax'   => false //We won't support Ajax for this table
                  ) );      
            $this->prepare_items();
            $this->display();           

    }
     function get_columns() {
        $columns = array(
            'id'    => 'ID',
            'user_login'     => 'User Name',
            'user_email'   => 'User Email'            
        );
        return $columns;
    }


    function column_default( $item, $column_name ) {
        switch( $column_name ) {
            case 'id':
            case 'user_login':
            case 'user_email':

                return $item[ $column_name ];
            default:
                return print_r( $item, true ) ;
        }
    }
    function prepare_items() {

        $example_data = array(
                array(
                        'id'        => 1,
                        'user_login'     => 'vasim',
                        'user_email'    => '[e-mail]'                        
                ),
                array(
                        'id'        => 2,
                        'user_login'     => 'Asma',
                        'user_email'    => '[e-mail]'                        
                ),
                array(
                        'id'        => 3,
                        'user_login'     => 'Nehal',
                        'user_email'    => '[e-mail]'                        
                ),
            );

        $columns = $this->get_columns();
        $hidden = array();
        $sortable = $this->get_sortable_columns();
        $this->_column_headers = array($columns, $hidden, $sortable);
        $this->items = $example_data;
    }

    public function WBU_adminMenu()
    {
            add_menu_page( 'Currently Logged In User', 'Banned User', 'manage_options', 'ban_admin_init', array($this,'ban_admin_init'));
    }
function ban_admin_init(){
        global $wpdb;

        $sql="SELECT * from {$wpdb->prefix}users";
        $sql_result=$wpdb->get_results($sql,'ARRAY_A');
        print_r($sql_result);
        //$this->items=$sql_result;     
    }

}

 global $Obj_Wp_Ban_User;

 $Obj_Wp_Ban_User=new Wp_Ban_User();

但是当我这样做时,我确实得到了这个错误：

Fatal error: Call to undefined function convert_to_screen() in
D:\xampp\htdocs\developplugin\wp-admin\includes\class-wp-list-table.PHP
on line 143

我做了一些研究,但不明白如何解决它.

有谁知道如何解决这个问题？

谢谢你的帮助！

最好的祝福.

解决方法:

抱歉我的英语不好,我是法国人.

我发现了这个问题.您的课程已更正(请参阅代码底部)：

<?PHP
/*
Plugin Name: My List Table Example
*/
 if ( ! class_exists( 'WP_List_Table' ) ) {
    require_once( ABSPATH . 'wp-admin/includes/class-wp-list-table.PHP' );
}


Class Wp_Ban_User extends WP_List_Table
{

    public function __construct()
    {
             parent::__construct( array(
                  'singular'=> 'wp_list_text_link', //Singular label
                  'plural' => 'wp_list_test_links', //plural label, also this well be one of the table css class
                  'ajax'   => false //We won't support Ajax for this table
                  ) );      
            $this->prepare_items();
            $this->display();           

    }

    function get_columns() {
        $columns = array(
            'id'    => 'ID',
            'user_login'     => 'User Name',
            'user_email'   => 'User Email'            
        );
        return $columns;
    }

    function column_default( $item, $column_name ) {
        switch( $column_name ) {
            case 'id':
            case 'user_login':
            case 'user_email':

                return $item[ $column_name ];
            default:
                return print_r( $item, true ) ;
        }
    }

    function prepare_items() {

        $example_data = array(
                array(
                        'id'        => 1,
                        'user_login'     => 'vasim',
                        'user_email'    => '[e-mail]'                        
                ),
                array(
                        'id'        => 2,
                        'user_login'     => 'Asma',
                        'user_email'    => '[e-mail]'                        
                ),
                array(
                        'id'        => 3,
                        'user_login'     => 'Nehal',
                        'user_email'    => '[e-mail]'                        
                ),
            );

        $columns = $this->get_columns();
        $hidden = array();
        $sortable = $this->get_sortable_columns();
        $this->_column_headers = array($columns, $hidden, $sortable);
        $this->items = $example_data;
    }

}


// Render your admin menu outside the class
function WBU_adminMenu()
{
    add_menu_page( 'Currently Logged In User', 'Banned User', 'manage_options', 'render_admin_page', 'render_admin_page');
}

// Create your menu outside the class
add_action('admin_menu','WBU_adminMenu');

// Render your page outside the class
function render_admin_page(){
    global $wpdb;

    $Obj_Wp_Ban_User=new Wp_Ban_User();
    $Obj_Wp_Ban_User->prepare_items();

    $sql="SELECT * from {$wpdb->prefix}users";
    $sql_result=$wpdb->get_results($sql,'ARRAY_A');
    print_r($sql_result);    
}

这个简单：解决错误调用未定义函数convert_to_screen()你需要：

>在课堂外添加菜单
>在课堂外添加admin_menu操作
>在课堂外渲染管理页面

3天后,它对我有用！