事件提供：

CartEvents::CART_EMPTY:清空购物车后触发。

CartEvents::CART_ENTITY_ADD:在将可购买实体添加到购物车后触发。

CartEvents::CART_ORDER_ITEM_UPDATE:在更新订单项目后激发。

CartEvents::CART_ORDER_ITEM_REMOVE:从购物车中删除订单项目后激发。

CartEvents::ORDER_ITEM_COMPARISON_FIELDS:在更改比较字段列表时触发-比较字段是Drupal commerce如何确定何时将商品添加到购物车中，该商品是否可以与现有商品组合。

实例：添加某个产品到购物车就会添加另外一个产品

我们在自定义模块中，定义一个事件订阅处理器：

modulename.services.yml

  1. services:
  2.   modulename.event_subscriber:
  3.     class: Drupal\modulename\EventSubscriber\CartEventSubscriber
  4.     arguments: ['@messenger', '@commerce_cart.cart_manager']
  5.     tags:
  6.       - { name: event_subscriber }

CartEventSubscriber.php

  1. <?php
  3. namespace Drupal\modulename\EventSubscriber;
  5. use Drupal\commerce_cart\CartManagerInterface;
  6. use Drupal\commerce_cart\Event\CartEntityAddEvent;
  7. use Drupal\commerce_cart\Event\CartEvents;
  8. use Drupal\commerce_product\Entity\ProductVariation;
  9. use Drupal\Core\Messenger\MessengerInterface;
  10. use Symfony\Component\EventDispatcher\EventSubscriberInterface;
  12. /**
  13.  * Cart Event Subscriber.
  14.  */
  15. class CartEventSubscriber implements EventSubscriberInterface {
  17.   /**
  18.    * The messenger.
  19.    *
  20.    * @var \Drupal\Core\Messenger\MessengerInterface
  21.    */
  22.   protected $messenger;
  24.   /**
  25.    * The cart manager.
  26.    *
  27.    * @var \Drupal\commerce_cart\CartManagerInterface
  28.    */
  29.   protected $cartManager;
  31.   /**
  32.    * Constructs event subscriber.
  33.    *
  34.    * @param \Drupal\Core\Messenger\MessengerInterface $messenger
  35.    *   The messenger.
  36.    */
  37.   public function __construct(MessengerInterface $messenger, CartManagerInterface $cart_manager) {
  38.     $this->messenger = $messenger;
  39.     $this->cartManager = $cart_manager;
  40.   }
  42.   /**
  43.    * {@inheritdoc}
  44.    */
  45.   public static function getSubscribedEvents() {
  46.     return [
  47.       CartEvents::CART_ENTITY_ADD => [['addToCart', 100]]
  48.     ];
  49.   }
  51.   /**
  52.    * Add a related product automatically
  53.    *
  54.    * @param \Drupal\commerce_cart\Event\CartEntityAddEvent $event
  55.    *   The cart add event.
  56.    *
  57.    * @throws \Drupal\Core\TypedData\Exception\ReadOnlyException
  58.    */
  59.   public function addToCart(CartEntityAddEvent $event) {
  60.     /** @var \Drupal\commerce_product\Entity\ProductVariationInterface $product_variation */
  61.     $product_variation = $event->getEntity();
  62.     if ($product_variation->getSku() === 'some_sku') {
  63.       $cart = $event->getCart();
  65.       // Load a known other product variation.
  66.       $variation = ProductVariation::load(5);
  68.       // Create a new order item based on the loaded variation.
  69.       $new_order_item = $this->cartManager->createOrderItem($variation);
  70.       $new_order_item->setQuantity(1);
  72.       // Add it to the cart.
  73.       $this->cartManager->addOrderItem($cart, $new_order_item);
  75.     }
  76.   }
  78. }