I have added a custom attribute in PDP page, I want to get that value in Observer/SaveToQuote.php to save in the quote table

Question

I have added a custom attribute in PDP page, I want to get that value in Observer/SaveToQuote.php to save in the quote table after the product is added to cart. I am using the event checkout_cart_product_add_after . Can anyone tell me how to do this? the custom attribute is comments

here is my pdp page code

<?php
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */

// phpcs:disable Magento2.Templates.ThisInTemplate.FoundThis

/**
 * Product view template
 *
 * @var $block \Magento\Catalog\Block\Product\View
 */
// form action  is here:- action="<?= $block->escapeUrl($block->getSubmitUrl($_product))




?>
<?php $_helper = $this->helper(Magento\Catalog\Helper\Output::class); ?>
<?php $_product = $block->getProduct(); ?>

<div class="product-add-form">
    <form data-product-sku="<?= $block->escapeHtml($_product->getSku()) ?>"
           method="post" action="<?= $block->escapeUrl($block->getSubmitUrl($_product))?>"
          id="product_addtocart_form"<?php if ($_product->getOptions()) :?> enctype="multipart/form-data"<?php endif; ?>>
        <input type="hidden" name="product" value="<?= (int)$_product->getId() ?>" />
        <input type="hidden" name="selected_configurable_option" value="" />
        <input type="hidden" name="related_product" id="related-products-field" value="" />
        <input type="hidden" name="item"  value="<?= (int)$block->getRequest()->getParam('id') ?>" />
          <h4>This is custom attribute comments section in PDP page </h4>
          Custom Attribute Comments :  <input type="text" id="comments" name="comments" value="">
        <?= $block->getBlockHtml('formkey') ?>
        <?= $block->getChildHtml('form_top') ?>
        <?php if (!$block->hasOptions()) :?>
            <?= $block->getChildHtml('product_info_form_content') ?>
        <?php else :?>
            <?php if ($_product->isSaleable() && $block->getOptionsContainer() == 'container1') :?>
                <?= $block->getChildChildHtml('options_container') ?>
            <?php endif;?>
        <?php endif; ?>

        <?php if ($_product->isSaleable() && $block->hasOptions() && $block->getOptionsContainer() == 'container2') :?>
            <?= $block->getChildChildHtml('options_container') ?>
        <?php endif;?>
        <?= $block->getChildHtml('form_bottom') ?>
    </form>
</div>

<script type="text/x-magento-init">
    {
        "[data-role=priceBox][data-price-box=product-id-<?= $block->escapeHtml($_product->getId()) ?>]": {
            "priceBox": {
                "priceConfig":  <?= /* @noEscape */ $block->getJsonConfig() ?>
            }
        }
    }
</script>

here is my Observer/SaveToQuote.php code

<?php

namespace DCKAP\Comments\Observer;

use Magento\Framework\Event\Observer;
use Magento\Framework\Event\ObserverInterface;
use Magento\Framework\App\RequestInterface;


class SaveToQuote implements ObserverInterface
{
    /**
     * Below is the method that will fire whenever the event runs!
     *
     * @param Observer $observer
     */

    /**
      *request parameter
      *
      *@param RequestInterface $request
      */

      /**
      * @var \Magento\Quote\Model\QuoteRepository
      */
       protected $quoteRepository;

     public function _costruct(
       \Magento\Quote\Model\QuoteRepository $quoteRepository
       )
     {
       $this->quoteRepository = $quoteRepository;

     }
    public function execute(Observer $observer)
    {
        $writer = new \Zend_Log_Writer_Stream(BP . '/var/log/savetoquote.log');
        $logger = new \Zend_Log();
        $logger->addWriter($writer);
        $quoteItem = $observer->getEvent()->getQuoteItem();
        $quote = $quoteItem->getQuote();
        $quoteId = $quote->getId();
        $logger->info("l45 the quoteId value is ".$quoteId);

         $product = $observer->getProduct(); // or $observer->getData('product');
         $comments = $product->getCustomAttribute('comments');
        // $comments = $this->getRequest()->getParam('comments');

        // $logger->info("l51 the comments value is ".$comments);

        
        
        $quote->setData('comments', $comments); // Fill data
        $this->quoteRepository->save($quote); // Save quote
    }
}

the comments value is empty in savetoquote.php

Any other idea to save the custom attribute in quote table is also appreciable.

Answer 1

Since "comments" is an input field, in your observer you need to get the data from Post data using RequestInterface

<?php

namespace DCKAP\Comments\Observer;

use Magento\Framework\Event\Observer;
use Magento\Framework\Event\ObserverInterface;
use Magento\Framework\App\RequestInterface;


class SaveToQuote implements ObserverInterface
{
    /**
     * Below is the method that will fire whenever the event runs!
     *
     * @param Observer $observer
     */

    /**
      *request parameter
      *
      *@param RequestInterface $request
      */

      /**
      * @var \Magento\Quote\Model\QuoteRepository
      */
       protected $quoteRepository;

     public function _costruct(
       ....
       RequestInterface $request
       )
     {
       ....
       $this->request = $request;

     }
    public function execute(Observer $observer)
    {
        ....
         $comments = $this->request->getPostValue('comments');
        // $comments = $this->getRequest()->getParam('comments');

        // $logger->info("l51 the comments value is ".$comments);



        $quote->setData('comments', $comments); // Fill data
        $this->quoteRepository->save($quote); // Save quote
    }
}