How to prevent order while placing order?

Question

I want to prevent order on checkout page. With the use of particular condition i need stop placing order.

When i click on place order button , my order should not be place and should redirect to cart page with error message.

Do anyone have idea on this?

Thanks!

Answer 1

Observer on event sales_order_place_before can prevent the order being placed. Example, if the order is below $100, order won't be placed, and the message will appear in checkout page. getData('order') returns Magento/Sales/Model/Order object. If you need to check the order items, you can use $order->getAllItems()

namespace Vendor\Module\Observer;

use Magento\Framework\Event\Observer;
use Magento\Framework\Event\ObserverInterface;
use Magento\Framework\Message\ManagerInterface as MessageManagerInterface;

class PreventOrder implements ObserverInterface
{

public function __construct(
   MessageManagerInterface $messageManager
) {
   $this->messageManager = $messageManager;
}

/**
 * @param Observer $observer
 * @return $this
 */
public function execute(Observer $observer)
 {
   $order = $observer->getEvent()->getData('order');
   $orderTotal = $order->getTotalDue();
   $threshold = 100;

   try {
     if ($orderTotal < $threshold) {
       $message = "Order is below the $100 minimum required!";
       $this->messageManager->addError(__($message));
       $this->_redirect('checkout/cart');
       return;
     }
   } catch (\Magento\Framework\Exception\Exception $e) {
     throw new \Magento\Framework\Exception\LocalizedException(
       __($e->getMessage())
     );
   }
 }

}

etc/events.xml file

  <event name="sales_order_place_before">
      <observer name="vendor_module_preventOrder" 
                instance="Vendor\Module\Observer\PreventOrder"/>
  </event>