`addProductsToCart` graphql mutation ignores `parent_sku` for configurable products

[damienwebdev]

Preconditions and environment

v2.4.7-p9

Steps to reproduce

When using the addProductsToCart mutation with parent_sku and a child sku (as documented here) to add a configurable product to the cart, the item is added as a SimpleCartItem instead of a ConfigurableCartItem. This results in incorrect product URLs, missing thumbnails, and missing configurable option data in the cart response.

1. Create a configurable product (e.g. ParentItem) with a simple child variant (e.g. ParentItem-Variant).
2. Add the product to the cart using addProductsToCart with parent_sku:

mutation {
  addProductsToCart(
    cartId: "{{cartId}}"
    cartItems: [
      {
        parent_sku: "ParentItem"
        sku: "ParentItem-Variant"
        quantity: 1
      }
    ]
  ) {
    cart {
      items {
        __typename
        product {
          name
          sku
          url_key
          thumbnail { url }
        }
        ... on ConfigurableCartItem {
          configurable_options {
            option_label
            value_label
          }
        }
      }
    }
  }
}

3. Observe the cart response.

Expected result

The cart item should be a ConfigurableCartItem with:

• product referencing the parent configurable product (correct url_key, thumbnail, etc.)
• configurable_options populated with the selected variant options
• configured_variant available for querying the selected simple product's data

Actual result

The cart item is a SimpleCartItem with:

• product referencing the child simple product directly
• url_key is the child's URL key (which typically has no frontend route)
• thumbnail is a placeholder image (the child simple product often has no image assigned)
• No configurable_options data

Additional information

There are two SuperAttributeDataProvider classes that handle resolving super_attribute data for configurable products:

Class	Used by	Handles parent_sku?
Magento\ConfigurableProductGraphQl\Model\Cart\BuyRequest\SuperAttributeDataProvider	addConfigurableProductsToCart	Yes
Magento\QuoteConfigurableOptions\Model\Cart\BuyRequest\SuperAttributeDataProvider	addProductsToCart	No

The newer provider (QuoteConfigurableOptions) only resolves super_attribute data from selected_options (base64-encoded UIDs). It does not read parent_sku or getParentSku() from the CartItem DTO at all, despite the CartItem class fully supporting it.

Additionally, Magento\Quote\Model\Cart\AddProductsToCart::addItemToCart loads the product by $cartItem->getSku() (line 160), which is the child SKU. Even if super_attribute were correctly resolved, Quote::addProduct() receives the child simple product, whose type instance (Simple) ignores super_attribute data entirely. The configurable type instance on the parent product is what processes super_attribute.

The QuoteConfigurableOptions SuperAttributeDataProvider should fall back to resolving super_attribute from parent_sku + child sku when selected_options does not contain configurable option data. The existing logic in ConfigurableProductGraphQl\SuperAttributeDataProvider already does this correctly.

Additionally, AddProductsToCart::addItemToCart should load the parent product (via parent_sku) instead of the child when parent_sku is present, so that the configurable type instance processes the buy request.

Release note

No response

Triage and priority

• Severity: S0 - Affects critical data or functionality and leaves users without workaround.
• Severity: S1 - Affects critical data or functionality and forces users to employ a workaround.
• Severity: S2 - Affects non-critical data or functionality and forces users to employ a workaround.
• Severity: S3 - Affects non-critical data or functionality and does not force users to employ a workaround.
• Severity: S4 - Affects aesthetics, professional look and feel, “quality” or “usability”.

[m2-assistant]

Hi @damienwebdev. Thank you for your report.
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[damienwebdev]

Here's a working plugin to fix this (but it sucks):

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <type name="Magento\Quote\Model\Cart\AddProductsToCart">
        <plugin name="resolveConfigurableFromParentSku" type="Vendor\ConfigurableCartItemGraphQl\Plugin\ResolveConfigurableFromParentSku"/>
    </type>
</config>

<?php declare(strict_types=1);

namespace Vendor\ConfigurableCartItemGraphQl\Plugin;

use Magento\Catalog\Api\Data\ProductInterface;
use Magento\Catalog\Api\ProductRepositoryInterface;
use Magento\ConfigurableProductGraphQl\Model\Options\Collection as OptionCollection;
use Magento\Framework\EntityManager\MetadataPool;
use Magento\Framework\Exception\NoSuchEntityException;
use Magento\Framework\GraphQl\Exception\GraphQlInputException;
use Magento\Framework\GraphQl\Exception\GraphQlNoSuchEntityException;
use Magento\Quote\Model\Cart\AddProductsToCart;
use Magento\Quote\Model\Cart\Data\CartItem;
use Magento\Quote\Model\Quote;

/**
 * When addProductsToCart is called with parent_sku + child sku,
 * the service loads the child simple product by its sku. This plugin
 * rebuilds those CartItems so that sku is the parent configurable SKU,
 * allowing the core code to load the correct product. The super_attribute
 * data is resolved from the parent/child relationship so that
 * Configurable::prepareForCartAdvanced processes the item correctly.
 */
class ResolveConfigurableFromParentSku
{
    public function __construct(
        private readonly ProductRepositoryInterface $productRepository,
        private readonly OptionCollection $optionCollection,
        private readonly MetadataPool $metadataPool,
    ) {
    }

    /**
     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
     */
    public function beforeAddItemsToCart(AddProductsToCart $subject, Quote $cart, array $cartItems): array
    {
        $rebuilt = [];
        foreach ($cartItems as $cartItem) {
            $parentSku = $cartItem->getParentSku();
            if ($parentSku === null || !empty($cartItem->getSelectedOptions())) {
                $rebuilt[] = $cartItem;
                continue;
            }

            $rebuilt[] = new CartItem(
                $parentSku,
                $cartItem->getQuantity(),
                $parentSku,
                $this->buildSelectedOptions($parentSku, $cartItem->getSku()),
                $cartItem->getEnteredOptions(),
            );
        }

        return [$cart, $rebuilt];
    }

    /**
     * Resolve configurable selected_options from parent/child SKU relationship.
     *
     * @return \Magento\Quote\Model\Cart\Data\SelectedOption[]
     */
    private function buildSelectedOptions(string $parentSku, string $childSku): array
    {
        try {
            $parentProduct = $this->productRepository->get($parentSku);
            $childProduct = $this->productRepository->get($childSku);
        } catch (NoSuchEntityException $e) {
            throw new GraphQlNoSuchEntityException(__('Could not find specified product.'));
        }

        $configurableProductLinks = $parentProduct->getExtensionAttributes()->getConfigurableProductLinks();
        if (!in_array($childProduct->getId(), $configurableProductLinks)) {
            throw new GraphQlInputException(__('Could not find specified product.'));
        }

        $linkField = $this->metadataPool->getMetadata(ProductInterface::class)->getLinkField();
        $this->optionCollection->addProductId((int)$parentProduct->getData($linkField));
        $options = $this->optionCollection->getAttributesByProductId((int)$parentProduct->getData($linkField));

        $selectedOptions = [];
        foreach ($options as $option) {
            $code = $option['attribute_code'];
            foreach ($option['values'] as $optionValue) {
                if ($optionValue['value_index'] === $childProduct->getData($code)) {
                    // Format: configurable/{attributeId}/{valueIndex}, base64-encoded
                    // phpcs:ignore Magento2.Functions.DiscouragedFunction
                    $selectedOptions[] = new \Magento\Quote\Model\Cart\Data\SelectedOption(
                        base64_encode("configurable/{$option['attribute_id']}/{$optionValue['value_index']}")
                    );
                    break;
                }
            }
        }

        if (empty($selectedOptions)) {
            throw new GraphQlInputException(
                __('The product with SKU %sku is out of stock.', ['sku' => $parentSku])
            );
        }

        return $selectedOptions;
    }
}

[m2-assistant]

Hi @engcom-Bravo. Thank you for working on this issue.
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[engcom-Bravo]

Hi @damienwebdev,

Thanks for your reporting and collaboration.

We have tried to reproduce the issue in Latest 2.4-develop instance and we are able to reproduce the issue.Kindly refer the screenshots.

The cart item is a SimpleCartItem.Hence Confirming the issue.

Thanks.