我使用以下代码将面板添加到管理菜单屏幕，以便用户能够将购物车链接添加到他们的菜单：

function my_add_meta_box() {
    add_meta_box( \'custom-meta-box\', __( \'Cart\' ), \'my_nav_menu_item_link_meta_box\', \'nav-menus\', \'side\', \'default\' );
}
add_action( \'admin_init\', \'my_add_meta_box\' );

function my_nav_menu_item_link_meta_box() {
    global $_nav_menu_placeholder, $nav_menu_selected_id;
    $_nav_menu_placeholder = 0 > $_nav_menu_placeholder ? $_nav_menu_placeholder - 1 : -1;
    ?>
    <div id="posttype-cart" class="posttypediv">
        <div id="tabs-panel-cart" class="tabs-panel tabs-panel-active">
            <ul id="cart-checklist" class="categorychecklist form-no-clear">
                <li>
                    <label class="menu-item-title">
                        <input type="checkbox" class="menu-item-checkbox" name="menu-item[<?php echo (int) $_nav_menu_placeholder; ?>][menu-item-object-id]" value="-1"> <?php esc_html_e( \'Cart\' ); ?>
                    </label>
                    <input type="hidden" class="menu-item-type" name="menu-item[<?php echo (int) $_nav_menu_placeholder; ?>][menu-item-type]" value="post_type">
                    <input type="hidden" class="menu-item-object" name="menu-item[<?php echo (int) $_nav_menu_placeholder; ?>][menu-item-object]" value="page">
                    <input type="hidden" class="menu-item-object-id" name="menu-item[<?php echo (int) $_nav_menu_placeholder; ?>][menu-item-object-id]" value="<?php echo get_option( \'woocommerce_cart_page_id\' ); ?>">
                    <input type="hidden" class="menu-item-title" name="menu-item[<?php echo (int) $_nav_menu_placeholder; ?>][menu-item-title]" value="<?php esc_html_e( \'Cart\' ); ?>">
                </li>
            </ul>
        </div>
        <p class="button-controls">
            <span class="add-to-menu">
                <input type="submit" <?php disabled( $nav_menu_selected_id, 0 ); ?> class="button-secondary submit-add-to-menu right" value="<?php esc_attr_e( \'Add to Menu\' ); ?>" name="add-post-type-menu-item" id="submit-posttype-cart">
                <span class="spinner"></span>
            </span>
        </p>
    </div>
    <?php
}

我的问题是，是否可以在前端的购物车菜单项标签旁边动态添加一个计数器，显示购物车中的项目数？如果是，如何？我认为wp_get_nav_menu_items 过滤器对此可能很有用，但如何识别其中的购物车菜单项，以便能够在前端动态修改其标签？

function my_get_nav_menu_items( $items ) {
    foreach ( $items as $item ) {
        if ( is_cart_menu_item( $item ) ) {
            // add a counter beside the Cart menu item label    
        }
    }
    return $items;
}
add_filter( \'wp_get_nav_menu_items\', \'my_get_nav_menu_items\', 20 );

function modify_cart_label_in_nav_menu_objects( $items, $args ) {
    foreach ( $items as $key => $item ) {
        if ( $item->object_id == (int) get_option( \'woocommerce_cart_page_id\' ) ) {
            if ( WC()->cart->get_cart_contents_count() > 0 ) {
                $item->title .= \' (\'. WC()->cart->get_cart_contents_count() . \')\';
            }
        }
    }
    return $items;
}
add_filter( \'wp_nav_menu_objects\', \'modify_cart_label_in_nav_menu_objects\', 10, 2 );

function modify_cart_label_in_nav_menu_objects( $items, $args ) {
    if($args->theme_location == \'primary\'){ 
        foreach ( $items as $key => $item ) {
            if ( $item->title == \'test\'  ) {
                $item->title .= \'(\'.WC()->cart->get_cart_contents_count().\')\';
            }
        }
    }
    return $items;
}
add_filter( \'wp_nav_menu_objects\', \'modify_cart_label_in_nav_menu_objects\', 10, 2 );