检查变量是否是WooCommerce中的类对象的实例

Question

我正在运行一个功能，通过该功能我可以检查用户上一次订单上是否有退款项目，如果有，则在结账时将积分作为负购物车费用。该功能适用于以前下过订单的用户，但会在网站上为新用户造成严重错误。

Fatal error: Uncaught Error: Call to a member function get_refunds() on bool in /wp-content/themes/my-theme/refunds.php:20 Stack trace:  
#0 /wp-includes/class-wp-hook.php(287): add_last_order_refund_total_at_checkout(Object(WC_Cart))  
#1 /wp-includes/class-wp-hook.php(311): WP_Hook->apply_filters('', Array)  
#2 /wp-includes/plugin.php(478): WP_Hook->do_action(Array)  
#3 /wp-content/plugins/woocommerce/includes/class-wc-cart.php(1714): do_action('woocommerce_car...', Object(WC_Cart))  
#4 /wp-content/plugins/woocommerce/includes/class-wc-cart-totals.php(270): WC_Cart->calculate_fees()  
#5 /wp-content/plugins/woocommerce/includes/class-wc-cart-totals.php(829): WC_Cart_Totals->get_fees_from_cart()  
#6 /wp-content/plugins/woocommerce/includes/class-wc- in /wp-content/themes/my-theme/refunds.php on line 20

以下是检查上一订单退款的代码：

//Check total of refunded items from last order - add as a fee at checkout
function add_last_order_refund_total_at_checkout($cart_object){
if ( is_admin() && ! defined( 'DOING_AJAX' ) )
return;
$user_id = get_current_user_id(); // The current user ID
$customer = new WC_Customer( $user_id );
$last_order = $customer->get_last_order();
$order_id = $last_order;
// Get the WC_Order Object instance (from the order ID)
$order = wc_get_order( $order_id );
// Get the Order refunds (array of refunds)
$order_refunds = $order->get_refunds();
$total_to_refund = $order->get_total_refunded()*(-1);//WIP need to check which items have tax

if (!empty($order_refunds)) WC()->cart->add_fee( 'Refund', $total_to_refund  );  
}
add_action( 'woocommerce_cart_calculate_fees', 'add_last_order_refund_total_at_checkout', 10, 1 );

我认为我需要首先检查用户是否有以前的订单，否则get_refund((会导致错误，因为他们没有订单要检查吗？我该如何安全地做到这一点？

Answer 1

如果您查看WC_Customerget_last_order()方法文档或源代码，您将看到：

/*
* @return WC_Order|false
*/

这意味着get_last_order()方法可以返回或者：

• WC_Order对象
• 或CCD_ 5布尔值

所以你可以在你的代码中使用：

$last_order = $customer->get_last_order();
if ( ! $last_order )  {
return; // Exit (Not an order)
}

为了避免这个错误。

---

现在您可以使用is_a()php条件函数来检查变量是否是来自特定Object类的，而不是其他类似的：

$last_order = $customer->get_last_order();
if ( ! is_a( $last_order, 'WC_Order' ) ) {
return; // Exit (Not an order)
}
// Your other code… 

或者，您可以为WC_Orderget_refunds()方法使用method_exists()php条件函数，以检查a变量是否来自特定Object类，而不是其他对象：

$last_order = $customer->get_last_order();
if ( ! method_exists( $last_order, 'get_refunds' ) )  {
return; // Exit (Not an order)
}
// Your other code…

这三种情况运行良好，避免了错误

Answer 2

尝试一下这种方式，添加了多个控件，请参阅注释

// Check total of refunded items from last order - add as a fee at checkout
function add_last_order_refund_total_at_checkout( $cart ) {
if ( is_admin() && ! defined( 'DOING_AJAX' ) )
return;
// The current user ID
$user_id = get_current_user_id();

// User id exists
if ( $user_id > 0 ) {
$customer = new WC_Customer( $user_id );

// Get last order
$last_order = $customer->get_last_order();
// True
if ( $last_order ) {
// Get the order id
$order_id = $last_order->get_id();

// Order ID exists
if ( is_numeric( $order_id ) ) {
// Get the WC_Order Object instance (from the order ID)
$order = wc_get_order( $order_id );
// Get the Order refunds (array of refunds)
$order_refunds = $order->get_refunds();

// NOT empty
if ( ! empty( $order_refunds) ) {
// WIP need to check which items have tax
$total_to_refund = $order->get_total_refunded();

// Add fee
$cart->add_fee( 'Refund', $total_to_refund  );
}
}
}
}
}
add_action( 'woocommerce_cart_calculate_fees', 'add_last_order_refund_total_at_checkout', 10, 1 );