通过ajax获取woocommerce订单总额

Question

我正在使用可以找到的woothemes的片段here。

这是前端的代码：

<?php global $woocommerce; ?>

<a class="cart-contents" href="<?php echo $woocommerce->cart->get_cart_url(); ?>" title="<?php _e('View your shopping cart', 'woothemes'); ?>"><?php echo sprintf(_n('%d item', '%d items', $woocommerce->cart->cart_contents_count, 'woothemes'), $woocommerce->cart->cart_contents_count);?> - <?php echo $woocommerce->cart->get_cart_total(); ?></a>

和后端（functions.php）

add_filter('add_to_cart_fragments', 'woocommerce_header_add_to_cart_fragment');

function woocommerce_header_add_to_cart_fragment( $fragments ) {
    global $woocommerce;

    ob_start();

    ?>
    <a class="cart-contents" href="<?php echo $woocommerce->cart->get_cart_url(); ?>" title="<?php _e('View your shopping cart', 'woothemes'); ?>"><?php echo sprintf(_n('%d item', '%d items', $woocommerce->cart->cart_contents_count, 'woothemes'), $woocommerce->cart->cart_contents_count);?> - <?php echo $woocommerce->cart->get_cart_total(); ?></a>
    <?php

    $fragments['a.cart-contents'] = ob_get_clean();

    return $fragments;

}

我希望在添加优惠券代码后获得可以找到的订单总额。

<?php echo $woocommerce->cart->get_cart_total(); ?>

上面的代码只会在添加产品时显示购物车的总金额，而不会显示总订单。将产品添加到购物车时，如何以折扣显示总订单？