Magento 2 – How to Get Product Image Data in Cart API

SOLVED!

In postman, we was selecting 'form-data', but you have to select 'raw' and insert a json object like this:

{
  "cart_item": {
    "quote_id": 5,
    "sku": "testing2",
    "qty": 1
  }
}

that should work! hope it helps.

Create extension attributes in extension_attributes.xml file like below.

<extension_attributes for="Magento\Quote\Api\Data\CartItemInterface">
        <attribute code="image_url" type="string" />
    </extension_attributes>

Add one observer for event "sales_quote_load_after" in observer add below code.

    use Magento\Framework\Event\ObserverInterface;
    use Magento\Catalog\Api\ProductRepositoryInterfaceFactory as ProductRepository;
    use Magento\Catalog\Helper\ImageFactory as ProductImageHelper;
    use Magento\Store\Model\StoreManagerInterface as StoreManager;
    use Magento\Store\Model\App\Emulation as AppEmulation;
    use Magento\Quote\Api\Data\CartItemExtensionFactory;

    class SalesQuoteLoadAfter implements ObserverInterface
    {   
        /**
         * @var ObjectManagerInterface
         */
        protected $_objectManager;

        /**
         * @var ProductRepository
         */
        protected $productRepository;

        /**
         *@var \Magento\Catalog\Helper\ImageFactory
         */
        protected $productImageHelper;

        /**
         *@var \Magento\Store\Model\StoreManagerInterface
         */
        protected $storeManager;

        /**
         *@var \Magento\Store\Model\App\Emulation
         */
        protected $appEmulation;

        /**
         * @var CartItemExtensionFactory
         */
        protected $extensionFactory;

        /**
         * @param \Magento\Framework\ObjectManagerInterface $objectManager
         * @param ProductRepository $productRepository
         * @param \Magento\Catalog\Helper\ImageFactory
         * @param \Magento\Store\Model\StoreManagerInterface
         * @param \Magento\Store\Model\App\Emulation
         * @param CartItemExtensionFactory $extensionFactory
         */
        public function __construct(
            \Magento\Framework\ObjectManagerInterface $objectManager,
            ProductRepository $productRepository,
            ProductImageHelper $productImageHelper,
            StoreManager $storeManager,
            AppEmulation $appEmulation,
            CartItemExtensionFactory $extensionFactory
        ) {
            $this->_objectManager = $objectManager;
            $this->productRepository = $productRepository;
            $this->productImageHelper = $productImageHelper;
            $this->storeManager = $storeManager;
            $this->appEmulation = $appEmulation;
            $this->extensionFactory = $extensionFactory;
        }

    public function execute(\Magento\Framework\Event\Observer $observer)
        {
            $quote = $observer->getQuote();

           /**
             * Code to add the items attribute to extension_attributes
             */
            foreach ($quote->getAllItems() as $quoteItem) {
                $product = $this->productRepository->create()->getById($quoteItem->getProductId());
                $itemExtAttr = $quoteItem->getExtensionAttributes();
                if ($itemExtAttr === null) {
                    $itemExtAttr = $this->extensionFactory->create();
                }
                $imageurl = $this->getImageUrl($product, 'product_thumbnail_image');
                $itemExtAttr->setImageUrl($imageurl);
                $quoteItem->setExtensionAttributes($itemExtAttr);
            }
            return;
        }

        /**
         * Helper function that provides full cache image url
         * @param \Magento\Catalog\Model\Product
         * @return string
         */
        protected function getImageUrl($product, string $imageType = '')
        {
            $storeId = $this->storeManager->getStore()->getId();

            $this->appEmulation->startEnvironmentEmulation($storeId, \Magento\Framework\App\Area::AREA_FRONTEND, true);
            $imageUrl = $imageUrl = $this->productImageHelper->create()->init($product, $imageType)->getUrl();

            $this->appEmulation->stopEnvironmentEmulation();

            return $imageUrl;
        }
    }

You will able to see response something like below

"items": [
        {
            "item_id": 215,
            "sku": "simple",
            "qty": 2,
            "name": "Simple product",
            "price": 840,
            "product_type": "simple",
            "quote_id": "184",
            "extension_attributes": {
                "image_url": "http://local.magento.com/media/catalog/product/cache/image/25x25/e9c3970ab036de70892d86c6d221abfe/c/4/c4.jpg"
            }
        }
    ]