Get quantity of simple products in configurable products on list.phtml

Question

I'm trying to get the qty of simple products in configurable products in the list page and it works with this code inside the product collection foreach:

$objectManager = \Magento\Framework\App\ObjectManager::getInstance();
$StockState = $objectManager->get('\Magento\CatalogInventory\Api\StockStateInterface');


foreach ($_productCollection as $_product):

$configProduct = $objectManager->create('Magento\Catalog\Model\Product')->load($_product->getId());

$_childrens = $configProduct->getTypeInstance()->getUsedProducts($configProduct);
 foreach ($_childrens as $child) {
  if ($StockState->getStockQty($child->getId(), $child->getStore()->getWebsiteId()) == 0) {
   echo "<span class='no-stock'>" . $child->getAttributeText('size') . "</span>";
  } else {
  echo "<span>" . $child->getAttributeText('size') . "</span>";
      }
}
endforeach;  

But this is very SLOW! how can I get the qty without using the objectManager?

how need to extend the ProductList class? How?

thank you in advance for your support

Answer 1

Solution:

$childProducts = $_product->getTypeInstance()->getUsedProducts($_product);
                            foreach ($childProducts as $child) {
                                $blockObj = $block->getLayout()->createBlock('Vendor\Module\Block\Product');
                                if ($blockObj->getStock($child) == 0) {
                                    echo "<span class='no-stock'>" . $child->getAttributeText('size') . "</span>";
                                } else {
                                    echo "<span>" . $child->getAttributeText('size') . "</span>";
                                }
                                $priceFormatted = $this->helper('Magento\Framework\Pricing\Helper\Data')->currency($child->getPrice(), true, false);
                            }

and custom block that extend template

namespace Vendor\Module\Block;

class Product extends \Magento\Framework\View\Element\Template
{
    protected $_scopeConfig;
    protected $_stockInterface;
    protected $_productRepository;

    public function __construct(
        \Magento\Framework\View\Element\Template\Context $context,
        \Magento\Framework\App\Config\ScopeConfigInterface $scopeConfig,
        \Magento\CatalogInventory\Api\StockStateInterface $stockInterface,
        \Magento\Catalog\Model\ProductRepository $productRepository
    ){
        $this->_scopeConfig = $scopeConfig;
        $this->_stockInterface = $stockInterface;
        $this->_productRepository = $productRepository;
        parent::__construct($context);
    }

    public function getStockMessage($productId){
        $_product = $this->getProductById($productId);
        $_stock = $this->getStock($_product);
        if($_stock <= $this->getThresoldQty()){
            return __('Only %1 left', $_stock);
        }
        return '';
    }

    public function getProductById($id)
    {
        return $this->_productRepository->getById($id);
    }

    public function getStock($_product)
    {
        return $this->_stockInterface->getStockQty($_product->getId(), $_product->getStore()->getWebsiteId());
    }

    public function getThresoldQty(){
        return $this->_scopeConfig->getValue('cataloginventory/options/stock_threshold_qty', \Magento\Store\Model\ScopeInterface::SCOPE_STORE);
    } 
}