Restrict Add To Cart According To Condition In Magento 2

Here we learn how to restrict ‘Add To Cart’ according to condition in Magento 2

For this i’ll use controller_action_predispatch_checkout_cart_add observer

1=> We create events.xml file in app/code/NameSpace/ModuleName/etc/frontend location and add following code

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
    <event name="controller_action_predispatch_checkout_cart_add">
        <observer name="yourcustomname" instance="NameSpace\ModuleName\Observer\RestrictAddToCart" />
    </event>
</config>

2=> Now we create your class where we check condition and restrict Add To Cart

Create RestrictAddToCart.php file at NameSpace\ModuleName\Observer\ location

<?php
namespace NameSpace\ModuleName\Observer;
 
use Magento\Framework\Event\ObserverInterface;
 
class RestrictAddToCart implements ObserverInterface
{
    /**
     * @var \Magento\Framework\Message\ManagerInterface
     */
    protected $_messageManager;
 
    /**
     * @param \Magento\Framework\Message\ManagerInterface $messageManager
     */
    public function __construct(
        \Magento\Framework\Message\ManagerInterface $messageManager
    )
    {
        $this->_messageManager = $messageManager;
    }
 
    /**
     * add to cart event handler.
     *
     * @param \Magento\Framework\Event\Observer $observer
     *
     * @return $this
     */
    public function execute(\Magento\Framework\Event\Observer $observer)
    {
        if (/* your condition */) {
                $this->_messageManager->addError(__('your custom message'));
                //set false if you not want to add product to cart
                $observer->getRequest()->setParam('product', false);
                return $this;
         }
 
        return $this;
    }
}

now flush your magento2 cache and it will working on your magento2 website.
after click add to cart button 1st it check condition and proceed according to condition
Thanks 🙂