我添加了一个元框，该框将列出特定帖子类型的帖子，保存时，它将使用选定的帖子id保存一个元键，但问题是它会重写帖子的永久链接，以将选定的帖子视为其父级，我不想这样做，我只需要存储选定的帖子id。这里的问题在哪里：

Found solution: 回答如下

function hfx_register_meta_boxes() {
    add_meta_box( \'select_hfx_workshop\', __( \'Workshop for\', HFX_DOMAIN ), \'hfx_select_workshop_parent_meta_box\', \'forum\', \'side\',
            \'core\');
}
add_action( \'add_meta_boxes\', \'hfx_register_meta_boxes\' );


    function hfx_select_workshop_parent_meta_box(){
        global $post;
        $selected = \'\';

        if(get_post_meta( $post->ID, \'parent_id\', true )){
            $selected = get_post_meta( $post->ID, \'workshop_id\', true );
        }

        if(post_type_exists( \'product\' )){
            $workshopsfx = get_posts(
            array(
                \'post_type\'   => \'product\',
                \'orderby\'     => \'title\',
                \'order\'       => \'ASC\',
                \'numberposts\' => -1
            )
        );

        if ( !empty( $workshopsfx ) ) {

            echo \'<select name="parent_id" class="widefat">\'; // !Important! Don\'t change the \'parent_id\' name attribute.
            echo \'<option value="">\'.esc_html__(\'Choose a workshop\', HFX_DoMAIN).\'</option>\';
            foreach ( $workshopsfx as $workshop ) {
                printf( \'<option value="%s"%s>%s</option>\', esc_attr( $workshop->ID ), selected( $workshop->ID, $selected, false ), esc_html( $workshop->post_title ) );
            }

            echo \'</select>\';
        }
        }
    }

function hfx_save_meta_box( $post_id ) {
    if ( defined( \'DOING_AUTOSAVE\' ) && DOING_AUTOSAVE ) return;
    if ( $parent_id = wp_is_post_revision( $post_id ) ) {
        $post_id = $parent_id;
    }
    $fields = [
        \'parent_id\',
    ];
    foreach ( $fields as $field ) {
        if ( array_key_exists( $field, $_POST ) ) {
            update_post_meta( $post_id, $field, sanitize_text_field( $_POST[$field] ) );
        }
     }
}
add_action( \'save_post\', \'hfx_save_meta_box\' );