Mfrhtyj

I am just modifying magento add to cart ajax functionality.
I want to check remain quantity of product if some is added to cart.
But i tried ,many ways but i did not success.
Instead of message manager, i want to display message in popup.

I tried

<?php

/**

 *

 * Copyright © Magento, Inc. All rights reserved.

 * See COPYING.txt for license details.

 */

namespace DevCheckoutControllerCart;



use MagentoCatalogApiProductRepositoryInterface;

use MagentoCheckoutModelCart as CustomerCart;

use MagentoFrameworkExceptionNoSuchEntityException;

use MagentoCatalogInventoryApiStockRegistryInterface;



/**

 * @SuppressWarnings(PHPMD.CouplingBetweenObjects)

 */

class Add extends MagentoCheckoutControllerCart

{

    /**

     * @var ProductRepositoryInterface

     */

    protected $productRepository;





    /**

     * @param MagentoFrameworkAppActionContext $context

     * @param MagentoFrameworkAppConfigScopeConfigInterface $scopeConfig

     * @param MagentoCheckoutModelSession $checkoutSession

     * @param MagentoStoreModelStoreManagerInterface $storeManager

     * @param MagentoFrameworkDataFormFormKeyValidator $formKeyValidator

     * @param CustomerCart $cart

     * @param ProductRepositoryInterface $productRepository

     * @codeCoverageIgnore

     */

    public function __construct(

        MagentoFrameworkAppActionContext $context,

        MagentoFrameworkAppConfigScopeConfigInterface $scopeConfig,

        MagentoCheckoutModelSession $checkoutSession,

        MagentoStoreModelStoreManagerInterface $storeManager,

        MagentoFrameworkDataFormFormKeyValidator $formKeyValidator,

        MagentoCatalogInventoryApiStockStateInterface $StockStateInterface,

        CustomerCart $cart,

        ProductRepositoryInterface $productRepository,

        StockRegistryInterface $StockRegistryInterface

    ) {

        parent::__construct(

            $context,

            $scopeConfig,

            $checkoutSession,

            $storeManager,

            $formKeyValidator,

            $cart

        );

        $this->productRepository = $productRepository;

        $this->storeManager = $storeManager;

        $this->stockRegistryInterface = $StockRegistryInterface;

    }



    /**

     * Initialize product instance from request data

     *

     * @return MagentoCatalogModelProduct|false

     */

    protected function _initProduct()

    {

        $productId = (int)$this->getRequest()->getParam('product');

        if ($productId) {

            $storeId = $this->_objectManager->get(

                MagentoStoreModelStoreManagerInterface::class

            )->getStore()->getId();

            try {

                return  $this->productRepository->getById($productId, false, $storeId);

            } catch (NoSuchEntityException $e) {

                return false;

            }

        }

        return false;

    }



    /**

     * Add product to shopping cart action

     *

     * @return MagentoFrameworkControllerResultRedirect

     * @SuppressWarnings(PHPMD.CyclomaticComplexity)

     */

    public function execute()

    {

        if (!$this->_formKeyValidator->validate($this->getRequest())) {

            return $this->resultRedirectFactory->create()->setPath('*/*/');

        }

        $params = $this->getRequest()->getParams(); 

            // Checking product quantity

            $productStockObj = $this->stockRegistryInterface->getStockItem($params['product']);  

            $remainQty = $productStockObj->getQty();   



            $requestFrom = '';

        if (array_key_exists('message-popup', $params)) {



        try {

            if (isset($params['qty'])) {

                $filter = new Zend_Filter_LocalizedToNormalized(

                    ['locale' => $this->_objectManager->get(

                        MagentoFrameworkLocaleResolverInterface::class

                    )->getLocale()]

                );

                $params['qty'] = $filter->filter($params['qty']);

            }



            $product = $this->_initProduct();

            $related = $this->getRequest()->getParam('related_product');



            /**

             * Check product availability

             */

            if (!$product) {

                return $this->goBack();

            }





            $this->cart->addProduct($product, $params);

            if (!empty($related)) {

                $this->cart->addProductsByIds(explode(',', $related));

            }



            $this->cart->save();



            /**

             * @todo remove wishlist observer MagentoWishlistObserverAddToCart

             */

            $this->_eventManager->dispatch(

                'checkout_cart_add_product_complete',

                ['product' => $product, 'request' => $this->getRequest(), 'response' => $this->getResponse()]

            );



            if (!$this->_checkoutSession->getNoCartRedirect(true)) {

                if (!$this->cart->getQuote()->getHasError()) {

                    if ($this->shouldRedirectToCart()) {

                        $message = __(

                            'You added %1 to your shopping cart.',

                            $product->getName()

                        );

                        $this->messageManager->addSuccessMessage($message);

                    } else {

                        $this->messageManager->addComplexSuccessMessage(

                            'addCartSuccessMessage',

                            [

                                'product_name' => $product->getName(),

                                'cart_url' => $this->getCartUrl(),

                            ]

                        );

                    }

                }

                return $this->goBack(null, $product);

            }

        } catch (MagentoFrameworkExceptionLocalizedException $e) {

            if ($this->_checkoutSession->getUseNotice(true)) {

                $this->messageManager->addNotice(

                    $this->_objectManager->get(MagentoFrameworkEscaper::class)->escapeHtml($e->getMessage())

                );

            } else {

                $messages = array_unique(explode("n", $e->getMessage()));

                foreach ($messages as $message) {

                    $this->messageManager->addError(

                        $this->_objectManager->get(MagentoFrameworkEscaper::class)->escapeHtml($message)

                    );

                }

            }



            $url = $this->_checkoutSession->getRedirectUrl(true);



            if (!$url) {

                $url = $this->_redirect->getRedirectUrl($this->getCartUrl());

            }



            return $this->goBack($url);

        } catch (Exception $e) {

            $this->messageManager->addException($e, __('We can't add this item to your shopping cart right now.'));

            $this->_objectManager->get(PsrLogLoggerInterface::class)->critical($e);

            return $this->goBack();

        }

       }

    }



    /**

     * Resolve response

     *

     * @param string $backUrl

     * @param MagentoCatalogModelProduct $product

     * @return $this|MagentoFrameworkControllerResultRedirect

     */

    protected function goBack($backUrl = null, $product = null)

    {

        if (!$this->getRequest()->isAjax()) {

            return parent::_goBack($backUrl);

        }



        $result = ;



        if ($backUrl || $backUrl = $this->getBackUrl()) {

            $result['backUrl'] = $backUrl;

        } else {

            if ($product && !$product->getIsSalable()) {

                $result['product'] = [

                    'statusText' => __('Out of stock')

                ];

            }

        }



        $this->getResponse()->representJson(

            $this->_objectManager->get(MagentoFrameworkJsonHelperData::class)->jsonEncode($result)

        );

    }



    /**

     * @return string

     */

    private function getCartUrl()

    {

        return $this->_url->getUrl('checkout/cart', ['_secure' => true]);

    }



    /**

     * @return bool

     */

    private function shouldRedirectToCart()

    {

        return $this->_scopeConfig->isSetFlag(

            'checkout/cart/redirect_to_cart',

            MagentoStoreModelScopeInterface::SCOPE_STORE

        );

    }

}

I used
MagentoCatalogInventoryApiStockRegistryInterface;
function getStockItem();

But i m not getting the remain stock of product.
I need to validate product stock before add to cart, and if not stock display no stock in popup.