Errors on disabling payment method programatically

Question

I was trying to disable the Cash on Delivery payment method using payment_method_is_active event and observer. But It stopped placing orders due to JavaSript error in the console.

Error in the checkout page:

    Uncaught TypeError: Unable to process binding "html: function(){return getInstructions() }"
Message: Cannot read properties of undefined (reading 'cashondelivery')
    at UiClass.getInstructions (cashondelivery-method.min.js:1:256)
    at html (eval at createBindingsStringEvaluator (knockout.min.js:285:237), <anonymous>:3:64)
    at evaluateValueAccessor (knockout.min.js:306:54)
    at knockout.min.js:330:181
    at update (knockout.min.js:399:434)
    at ko.dependentObservable.disposeWhenNodeIsRemoved (knockout.min.js:336:74)
    at Function.evaluateImmediate_CallReadThenEndDependencyDetection (knockout.min.js:212:240)
    at Function.evaluateImmediate_CallReadWithDependencyDetection (knockout.min.js:207:626)
    at Function.evaluateImmediate (knockout.min.js:206:46)
    at ko.computed.ko.dependentObservable (knockout.min.js:195:71)

Observer

<?php
declare(strict_types=1);

namespace Vendor\Module\Observer;

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

class TogglePaymentMethods implements ObserverInterface
{
    /**
     * @param Observer $observer
     * @return void
     */
    public function execute(Observer $observer)
    {
        $result = $observer->getEvent()->getResult();
        $method_instance = $observer->getEvent()->getMethodInstance();
        $quote = $observer->getEvent()->getQuote();

        if($method_instance->getCode() == 'cashondelivery'){
            $result->setData('is_available', false);
        }
    }

}

Answer 1

Try to use this code in observer

<?php
declare(strict_types=1);
namespace Vendor\Module\Observer;

use Magento\Framework\Event\ObserverInterface;
    
class TogglePaymentMethods implements ObserverInterface
{
    public function execute(\Magento\Framework\Event\Observer $observer)
    {
       if($observer->getEvent()->getMethodInstance()->getCode()=="cashondelivery"){
             $checkResult = $observer->getEvent()->getResult();
             $checkResult->setData('is_available', false); 
       }
    }
}

Also, you have set is_available true, it needs to be false for disabling payment method

Answer 2

you can use a plugin on the Magento\OfflinePayments\Model\Checkmo class.

1. Create the file app/code/[Vendor]/[Module]/etc/di.xml and add the following code:

   <config>
        <type name="Magento\OfflinePayments\Model\Checkmo">
            <plugin name="disable_checkmo_payment" type="[Vendor]\[Module]\Plugin\Model\Checkmo" sortOrder="1"/>
        </type>
   </config>
   

2. Create the file app/code/[Vendor]/[Module]/Plugin/Model/Checkmo.php and add the following code:

   <?php
   
    namespace [Vendor]\[Module]\Plugin\Model;
   
    use Magento\OfflinePayments\Model\Checkmo as CheckmoModel;
   
    class Checkmo
    {
        /**
         * Disable the Cash on Delivery payment method
         *
         * @param CheckmoModel $subject
         * @param bool $result
         * @return bool
         */
        public function afterIsAvailable(CheckmoModel $subject, $result)
        {
            // Check if the payment method is Cash on Delivery
            if ($subject->getCode() == 'checkmo') {
                // Disable the payment method
                return false;
            }
   
            return $result;
        }
    }