Avoid loading the order collection twice for customer orders GraphQL query

app/code/Magento/SalesGraphQl/Model/OrderItem/DataProvider.php

@@ -64,6 +64,13 @@ class DataProvider
      */
     private $orderItemList = [];
 
+    /**
+     * Orders already loaded upstream, keyed by entity id, so the item load does not reload them.
+     *
+     * @var OrderInterface[]
+     */
+    private $providedOrders = [];
+
     /**
      * @param OrderItemRepositoryInterface $orderItemRepository
      * @param ProductRepositoryInterface $productRepository
@@ -101,6 +108,16 @@ public function addOrderItemId(int $orderItemId): void
         }
     }
 
+    /**
+     * Provide an already-loaded order so the item fetch can reuse it instead of reloading it from the DB
+     *
+     * @param OrderInterface $order
+     */
+    public function addOrder(OrderInterface $order): void
+    {
+        $this->providedOrders[(int)$order->getEntityId()] = $order;
+    }
+
     /**
      * Get order item by item id
      *
@@ -207,22 +224,27 @@ function ($orderItem) {
      */
     private function fetchOrders(array $orderItems): array
     {
-        $orderIds = array_map(
-            function ($orderItem) {
-                return $orderItem->getOrderId();
-            },
-            $orderItems
-        );
-
-        $searchCriteria = $this->searchCriteriaBuilder
-            ->addFilter('entity_id', $orderIds, 'in')
-            ->create();
-        $orders = $this->orderRepository->getList($searchCriteria)->getItems();
+        // Start from orders the caller already loaded (e.g. the customer's order list resolver) so they
+        // are not queried again, and only load the ids that were not provided.
+        $orderList = $this->providedOrders;
+        $missingOrderIds = [];
+        foreach ($orderItems as $orderItem) {
+            $orderId = (int)$orderItem->getOrderId();
+            if (!isset($orderList[$orderId])) {
+                $missingOrderIds[$orderId] = $orderId;
+            }
+        }
 
-        $orderList = [];
-        foreach ($orders as $order) {
-            $orderList[$order->getEntityId()] = $order;
+        if (!empty($missingOrderIds)) {
+            $searchCriteria = $this->searchCriteriaBuilder
+                ->addFilter('entity_id', $missingOrderIds, 'in')
+                ->create();
+            $orders = $this->orderRepository->getList($searchCriteria)->getItems();
+            foreach ($orders as $order) {
+                $orderList[(int)$order->getEntityId()] = $order;
+            }
         }
+
         return $orderList;
     }
 

app/code/Magento/SalesGraphQl/Model/Resolver/CreditMemo/CreditMemoItems.php

@@ -67,6 +67,7 @@ public function resolve(
         $creditMemoModel = $value['model'];
         /** @var OrderInterface $parentOrderModel */
         $parentOrderModel = $value['order'];
+        $this->orderItemProvider->addOrder($parentOrderModel);
 
         return $this->valueFactory->create(
             $this->getCreditMemoItems($parentOrderModel, $creditMemoModel->getItems())

app/code/Magento/SalesGraphQl/Model/Resolver/Invoice/InvoiceItems.php

@@ -67,6 +67,7 @@ public function resolve(
         $invoiceModel = $value['model'];
         /** @var OrderInterface $parentOrderModel */
         $parentOrderModel = $value['order'];
+        $this->orderItemProvider->addOrder($parentOrderModel);
 
         return $this->valueFactory->create(
             $this->getInvoiceItems($parentOrderModel, $invoiceModel->getItems())

app/code/Magento/SalesGraphQl/Model/Resolver/OrderItems.php

@@ -54,6 +54,7 @@ public function resolve(Field $field, $context, ResolveInfo $info, ?array $value
         }
         /** @var OrderInterface $parentOrder */
         $parentOrder = $value['model'];
+        $this->orderItemProvider->addOrder($parentOrder);
         $orderItemIds = [];
         foreach ($parentOrder->getItems() as $item) {
             if (!$item->getParentItemId()) {

app/code/Magento/SalesGraphQl/Test/Unit/Model/OrderItem/DataProviderTest.php

@@ -0,0 +1,183 @@
+<?php
+/**
+ * Copyright 2026 Adobe
+ * All Rights Reserved.
+ */
+declare(strict_types=1);
+
+namespace Magento\SalesGraphQl\Test\Unit\Model\OrderItem;
+
+use Magento\Catalog\Api\Data\ProductSearchResultsInterface;
+use Magento\Catalog\Api\ProductRepositoryInterface;
+use Magento\Framework\Api\SearchCriteria;
+use Magento\Framework\Api\SearchCriteriaBuilder;
+use Magento\Sales\Api\Data\OrderInterface;
+use Magento\Sales\Api\Data\OrderItemSearchResultInterface;
+use Magento\Sales\Api\Data\OrderSearchResultInterface;
+use Magento\Sales\Api\OrderItemRepositoryInterface;
+use Magento\Sales\Api\OrderRepositoryInterface;
+use Magento\Sales\Model\Order\Item as OrderItemModel;
+use Magento\SalesGraphQl\Model\OrderItem\DataProvider;
+use Magento\SalesGraphQl\Model\OrderItem\OptionsProcessor;
+use Magento\Tax\Helper\Data as TaxHelper;
+use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @SuppressWarnings(PHPMD.CouplingBetweenObjects)
+ */
+class DataProviderTest extends TestCase
+{
+    /**
+     * @var OrderItemRepositoryInterface|MockObject
+     */
+    private $orderItemRepository;
+
+    /**
+     * @var ProductRepositoryInterface|MockObject
+     */
+    private $productRepository;
+
+    /**
+     * @var OrderRepositoryInterface|MockObject
+     */
+    private $orderRepository;
+
+    /**
+     * @var SearchCriteriaBuilder|MockObject
+     */
+    private $searchCriteriaBuilder;
+
+    /**
+     * @var OptionsProcessor|MockObject
+     */
+    private $optionsProcessor;
+
+    /**
+     * @var TaxHelper|MockObject
+     */
+    private $taxHelper;
+
+    /**
+     * @var DataProvider
+     */
+    private $dataProvider;
+
+    /**
+     * @inheritdoc
+     */
+    protected function setUp(): void
+    {
+        $this->orderItemRepository = $this->createMock(OrderItemRepositoryInterface::class);
+        $this->productRepository = $this->createMock(ProductRepositoryInterface::class);
+        $this->orderRepository = $this->createMock(OrderRepositoryInterface::class);
+        $this->searchCriteriaBuilder = $this->createMock(SearchCriteriaBuilder::class);
+        $this->optionsProcessor = $this->createMock(OptionsProcessor::class);
+        $this->taxHelper = $this->createMock(TaxHelper::class);
+
+        $this->searchCriteriaBuilder->method('addFilter')->willReturnSelf();
+        $this->searchCriteriaBuilder->method('create')->willReturn($this->createMock(SearchCriteria::class));
+        $this->optionsProcessor->method('getItemOptions')
+            ->willReturn(['selected_options' => [], 'entered_options' => []]);
+
+        $this->dataProvider = new DataProvider(
+            $this->orderItemRepository,
+            $this->productRepository,
+            $this->orderRepository,
+            $this->searchCriteriaBuilder,
+            $this->optionsProcessor,
+            $this->taxHelper
+        );
+    }
+
+    public function testProvidedOrderIsNotReloadedFromRepository(): void
+    {
+        $orderId = 5;
+        $orderItemId = 42;
+        $orderItem = $this->createOrderItemMock($orderItemId, $orderId, 7);
+        $order = $this->createOrderMock($orderId, 'USD');
+
+        $this->stubItemAndProductLists([$orderItem]);
+        // The order is already loaded upstream, so it must not be queried again.
+        $this->orderRepository->expects($this->never())->method('getList');
+
+        $this->dataProvider->addOrderItemId($orderItemId);
+        $this->dataProvider->addOrder($order);
+        $result = $this->dataProvider->getOrderItemById($orderItemId);
+
+        $this->assertSame('USD', $result['product_sale_price']['currency']);
+    }
+
+    public function testMissingOrderFallsBackToRepository(): void
+    {
+        $orderId = 9;
+        $orderItemId = 77;
+        $orderItem = $this->createOrderItemMock($orderItemId, $orderId, 3);
+        $order = $this->createOrderMock($orderId, 'EUR');
+
+        $this->stubItemAndProductLists([$orderItem]);
+        // No order was provided, so the repository must be queried for the missing id.
+        $orderSearchResult = $this->createMock(OrderSearchResultInterface::class);
+        $orderSearchResult->method('getItems')->willReturn([$order]);
+        $this->orderRepository->expects($this->once())->method('getList')->willReturn($orderSearchResult);
+
+        $this->dataProvider->addOrderItemId($orderItemId);
+        $result = $this->dataProvider->getOrderItemById($orderItemId);
+
+        $this->assertSame('EUR', $result['product_sale_price']['currency']);
+    }
+
+    /**
+     * @param OrderItemModel[] $orderItems
+     */
+    private function stubItemAndProductLists(array $orderItems): void
+    {
+        $itemSearchResult = $this->createMock(OrderItemSearchResultInterface::class);
+        $itemSearchResult->method('getItems')->willReturn($orderItems);
+        $this->orderItemRepository->method('getList')->willReturn($itemSearchResult);
+
+        $productSearchResult = $this->createMock(ProductSearchResultsInterface::class);
+        $productSearchResult->method('getItems')->willReturn([]);
+        $this->productRepository->method('getList')->willReturn($productSearchResult);
+    }
+
+    /**
+     * @param int $itemId
+     * @param int $orderId
+     * @param int $productId
+     * @return OrderItemModel|MockObject
+     */
+    private function createOrderItemMock(int $itemId, int $orderId, int $productId)
+    {
+        $orderItem = $this->createMock(OrderItemModel::class);
+        // getItemId() is a DB value surfaced as a string; the provider base64_encodes it.
+        $orderItem->method('getItemId')->willReturn((string)$itemId);
+        $orderItem->method('getOrderId')->willReturn($orderId);
+        $orderItem->method('getProductId')->willReturn($productId);
+        $orderItem->method('getName')->willReturn('Item name');
+        $orderItem->method('getSku')->willReturn('sku-' . $itemId);
+        $orderItem->method('getProductType')->willReturn('simple');
+        $orderItem->method('getChildrenItems')->willReturn([]);
+        $orderItem->method('getStatus')->willReturn('Ordered');
+        $orderItem->method('getDiscountAmount')->willReturn(0);
+        $orderItem->method('getPrice')->willReturn(10.0);
+        $orderItem->method('getPriceInclTax')->willReturn(12.0);
+        return $orderItem;
+    }
+
+    /**
+     * @param int $orderId
+     * @param string $currency
+     * @return OrderInterface|MockObject
+     */
+    private function createOrderMock(int $orderId, string $currency)
+    {
+        $order = $this->createMock(OrderInterface::class);
+        $order->method('getEntityId')->willReturn($orderId);
+        $order->method('getStoreId')->willReturn(1);
+        $order->method('getOrderCurrencyCode')->willReturn($currency);
+        $order->method('getDiscountDescription')->willReturn(null);
+        $order->method('getDiscountAmount')->willReturn(0);
+        return $order;
+    }
+}