public function __construct( CartRepositoryInterface $quoteRepository, OrderRepositoryInterface $orderRepository ) $this->quoteRepository = $quoteRepository; $this->orderRepository = $orderRepository;

public function getAppliedCouponForItem($itemId)

use Magento\Sales\Model\ResourceModel\Order\CollectionFactory; public function getCouponCodesFromOrders(CollectionFactory $orderCollectionFactory, array $orderIds)

public function fromOrder(int $orderId): ?string

public function __construct(CollectionFactory $couponCollectionFactory)

Often needed for order export, invoices, or customer history pages.