wordpress插件，如何为自定义帖子类型添加重写规则

Question

我已使用此代码创建自定义帖子类型

public static function init() {
    add_action( 'init', array( __CLASS__, 'register_post_types' ), 10);
    add_filter('template_include', array( __CLASS__, 'exam_template'), 1);
}

public static function register_post_types() {
    $labels = array(
        'name'               => __( 'Exam Online', 'Edinnova' ),
        'singular_name'      => 'Exam',
        'add_new'            => 'Add New',
        'add_new_item'       => 'Add New '.'Exam Online',
        'edit_item'          => 'Edit '.'Exam Online',
        'new_item'           => 'New '.'Exam Online',
        'all_items'          => 'All '.'Exams',
        'view_item'          => 'View '.'Exam Online',
        'search_items'       => 'Search '.'Exam',
        'not_found'          =>  'No '.'Exam'.' Found',
        'not_found_in_trash' => 'No '.'Exam'.' Found In Trash',
        'parent_item_colon'  => '',
        'menu_name'          => 'Exam Online'
    );

    $args = array(
        'labels'             => $labels,
        'public'             => false,
        'publicly_queryable' => true,
        'show_ui'            => true,
        'show_in_menu'       => false,
        'query_var'          => true,
        'capability_type'    => 'post',
        'has_archive'        => false,
        'hierarchical'       => false,
        'menu_position'      => null,
        'supports'           => array( 'title', 'editor','thumbnail','author'),
        'capability_type'     => 'post',

    );
    register_post_type( 'exam_online', $args );

    add_rewrite_rule('exam_online/([^ /] +)/review', '?index.php&exam=$params[1]&review=yes', 'top');

    add_filter('query_vars', function($_vars) {
        $_vars[] = 'review';

        return $_vars;
    });

    flush_rewrite_rules();
}

public static function exam_template($template) {
        if (get_post_type() == 'exam_online') {
            if ($_GET['review'] == 'yes') {
                $single_template = dirname(__dir__).'/templates/review-exam_online.php';
            }

            $single_template = dirname(__dir__).'/templates/single-exam_online.php';
        }

        return $single_template;
    }

当我创建自定义帖子然后在首页上查看时，我有这个网址<domain>/exam_online/<post-url-slug>/

URL上方将按单个模板显示

并且我希望网址<domain>/exam_online/<post-url-slug>/review通过评论模板显示

但是可能有些问题，当我转到网址<domain>/exam_online/<post-url-slug>/review时始终返回404。

我的代码有什么问题？请帮忙！

另一个奇怪的是，当我使用插件Debug Bar Rewrite Rules时，wordpress似乎无法识别我的重写规则，因为当我搜索正则表达式规则时没有结果。