how to get error message if QTY exceed ask QTY

Question

How to get error message if ask QTY higher than the QTY in stock. like IsSalableWithReservationsCondition.php file that echo the "The requested qty is not available" how to use the same logic but use the value in the attribute I created as a quantity of that product selected and if ask QTY higher than the value in that attribute echo this message "The requested qty is not available"

Answer 1

Your issue is related to incorrect logic of extend original classes.

Your are trying to copy paste target (\Magento\Catalog\Block\Product\View\Attributes) class and extend from the same target class (\Magento\Catalog\Block\Product\View\Attributes) instead of it parent.

I don't know and see what is reason to overwrite this class and fully extend it.

To solve your issue you can change extends to \Magento\Framework\View\Element\Template or remove __construct method.

Answer 2

Update your Attributes.php with

<?php

namespace extendAttribute\showAttribute\Block\Product\View;

use Magento\Catalog\Block\Product\View\Attributes as ExtendAttribute;
use Magento\Catalog\Model\Product;
use Magento\Framework\Phrase;
use Magento\Framework\Pricing\PriceCurrencyInterface;

/**
 * Attributes attributes block
 *
 * @api
 * @since 100.0.2
**/
class Attributes extends ExtendAttribute
{
    /**
     * @var Product
     */
    protected $_product = null;

    /**
     * Core registry
     *
     * @var \Magento\Framework\Registry
     */
    protected $_coreRegistry = null;

    /**
     * @var PriceCurrencyInterface
     */
    protected $priceCurrency;

    /**
     * @param \Magento\Framework\View\Element\Template\Context $context
     * @param \Magento\Framework\Registry $registry
     * @param PriceCurrencyInterface $priceCurrency
     * @param array $data
     */
    public function __construct(
        \Magento\Framework\View\Element\Template\Context $context,
        \Magento\Framework\Registry $registry,
        PriceCurrencyInterface $priceCurrency,
        array $data = []
    ) {
        $this->priceCurrency = $priceCurrency;
        $this->_coreRegistry = $registry;
        parent::__construct($context, $registry, $priceCurrency, $data);
    }

    /**
     * Returns a Product
     *
     * @return Product
     */
    public function getProduct()
    {
        if (!$this->_product) {
            $this->_product = $this->_coreRegistry->registry('product');
        }
        return $this->_product;
    }

    /**
     * $excludeAttr is optional array of attribute codes to exclude them from additional data array
     *
     * @param array $excludeAttr
     * @return array
     * @throws \Magento\Framework\Exception\LocalizedException
     */
    public function getAdditionalData(array $excludeAttr = [])
    {
        $data = [];
        $product = $this->getProduct();
        $attributes = $product->getAttributes();
        foreach ($attributes as $attribute) {
            if ($this->isVisibleOnFrontend($attribute, $excludeAttr)) {
                $value = $attribute->getFrontend()->getValue($product);

                if ($value instanceof Phrase) {
                    $value = (string)$value;
                } elseif ($attribute->getFrontendInput() == 'price' && is_string($value)) {
                    $value = $this->priceCurrency->convertAndFormat($value);
                }

                if (is_string($value) && strlen(trim($value))) {
                    $data[$attribute->getAttributeCode()] = [
                        'label' => $attribute->getStoreLabel(),
                        'value' => $value,
                        'code' => $attribute->getAttributeCode(),
                    ];
                };
            }
        }
        return $data;
    }

    /**
     * Determine if we should display the attribute on the front-end
     *
     * @param \Magento\Eav\Model\Entity\Attribute\AbstractAttribute $attribute
     * @param array $excludeAttr
     * @return bool
     * @since 103.0.0
     */
    protected function isVisibleOnFrontend(
        \Magento\Eav\Model\Entity\Attribute\AbstractAttribute $attribute,
        array $excludeAttr
    ) {
        return ($attribute->getIsVisibleOnFront() && !in_array($attribute->getAttributeCode(), $excludeAttr));
    }
}

Hope this works for you!