Override model function Magento 2

Question

I want to override one of the function in Magento core model which is located in

vendor\magento\module-sales\Model\Order\Email\Sender\OrderSender.php

<?php
/**
 * Copyright © 2016 Magento. All rights reserved.
 * See COPYING.txt for license details.
 */
namespace Magento\Sales\Model\Order\Email\Sender;

use Magento\Payment\Helper\Data as PaymentHelper;
use Magento\Sales\Model\Order;
use Magento\Sales\Model\Order\Email\Container\OrderIdentity;
use Magento\Sales\Model\Order\Email\Container\Template;
use Magento\Sales\Model\Order\Email\Sender;
use Magento\Sales\Model\ResourceModel\Order as OrderResource;
use Magento\Sales\Model\Order\Address\Renderer;
use Magento\Framework\Event\ManagerInterface;

/**
 * Class OrderSender
 * @SuppressWarnings(PHPMD.CouplingBetweenObjects)
 */
class OrderSender extends Sender
{
  protected function prepareTemplate(Order $order)
    {
        $transport = [
            'order' => $order, 
            'billing' => $order->getBillingAddress(),
            'payment_html' => $this->getPaymentHtml($order),
            'store' => $order->getStore(),
            'formattedShippingAddress' => $this->getFormattedShippingAddress($order),
            'formattedBillingAddress' => $this->getFormattedBillingAddress($order),
        ];

        $transport = new \Magento\Framework\DataObject($transport);

        $this->eventManager->dispatch(
            'email_order_set_template_vars_before',
            ['sender' => $this, 'transport' => $transport]
        );

        $this->templateContainer->setTemplateVars($transport->getData());

        parent::prepareTemplate($order);
    }
}

I just want to add additional data to $transport array variable from my custom extension, but it seems not working because when I call the additional data it didn't print anything, here's what i've done:

etc/di.xml

<?xml version="1.0" ?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <preference for="Magento\Sales\Model\Order\Email\Sender\OrderSender" type="Namespace\Module\Model\Order\Email\Sender\OrderSender"/>
</config>

Namespace\Module\Model\Order\Email\Sender\OrderSender.php

<?php
/**
 * Copyright © 2016 Magento. All rights reserved.
 * See COPYING.txt for license details.
 */
namespace Namespace\Module\Model\Order\Email\Sender;

use Magento\Payment\Helper\Data as PaymentHelper;
use Magento\Sales\Model\Order;
use Magento\Sales\Model\Order\Email\Container\OrderIdentity;
use Magento\Sales\Model\Order\Email\Container\Template;
use Magento\Sales\Model\Order\Email\Sender;
use Magento\Sales\Model\ResourceModel\Order as OrderResource;
use Magento\Sales\Model\Order\Address\Renderer;
use Magento\Framework\Event\ManagerInterface;

/**
 * Class OrderSender
 * @SuppressWarnings(PHPMD.CouplingBetweenObjects)
 */
class OrderSender extends \Magento\Sales\Model\Order\Email\Sender\OrderSender
{


    public function prepareTemplate(Order $order)
    {

        $transport = [
            'order' => $order,
            'billing' => $order->getBillingAddress(),
            'payment_html' => $this->getPaymentHtml($order),
            'test' => '<p> Yoo Yeezy </p>',
            'store' => $order->getStore(),
            'formattedShippingAddress' => $this->getFormattedShippingAddress($order),
            'formattedBillingAddress' => $this->getFormattedBillingAddress($order),
        ];
        $transport = new \Magento\Framework\DataObject($transport);

        $this->eventManager->dispatch(
            'email_order_set_template_vars_before',
            ['sender' => $this, 'transport' => $transport]
        );

        $this->templateContainer->setTemplateVars($transport->getData());

        parent::prepareTemplate($order);
    }


}

Answer 1

Depending on what kind of data you want to add, you might want to use an observer instead of rewriting the model:

etc/events.xml

<?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="email_order_set_template_vars_before">
        <observer name="add_extra_data_to_transport" instance="Vendor\Module\Observer\AddExtraDataToTransport" />
    </event>
</config>

Then create Observer\AddExtraDataToTransport.php

<?php

namespace Vendor\Module\Observer;

use Magento\Framework\Event\ObserverInterface;

class AddExtraDataToTransport implements ObserverInterface
{  
    public function execute(\Magento\Framework\Event\Observer $observer)
    {
        $transport = $observer->getEvent()->getTransport();
        $transport['test'] = '<p> Yoo Yeezy </p>';
        if ($transport['payment_html'] == 'transfer') {
            $transport['payment_html'] = 'test';
        }
    }
}

Answer 2

Use an observer instead of rewriting the model:

etc/events.xml

<?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="email_order_set_template_vars_before">
        <observer name="add_extra_data_to_transport" instance="Vendor\Module\Observer\AddExtraDataToTransport" />
    </event>
</config>

Then create Observer\AddExtraDataToTransport.php and change data

<?php
namespace Vendor\Module\Observer;

use Magento\Framework\Event\ObserverInterface;

class AddExtraDataToTransport implements ObserverInterface
{  
    public function execute(\Magento\Framework\Event\Observer $observer)
    {
        $transport = $observer->getTransport();
        if ($transport->getPaymentHtml == 'transfer') {
            $transport->setPaymentHtml('test');
        }
    }
}

Checked at Magento 2.2.2

Answer 3

Depending on what kind of data you want to add, you might want to use an observer instead of rewriting the model:

Method to use custom variables in transactional Email in Magento 2:

1 - Create registration.php file in app\code\[Vendor]\[Namespace]\

<?php
 \Magento\Framework\Component\ComponentRegistrar::register(
     \Magento\Framework\Component\ComponentRegistrar::MODULE,
        '[Vendor]_[Namespace]',
          __DIR__
  );

2 - create module.xml file in app\code\[Vendor]\[Namespace]\etc

<?xml version="1.0"?>
    <config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
        <module name="[Vendor]_[Namespace]" setup_version="1.0.0"/>
    </config>

3 - Create events.xml file in app\code\[Vendor]\[Namespace]\etc

<?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="email_order_set_template_vars_before">
            <observer name="add_extra_data_to_transport" instance="[Vendor]\[Namespace]\Observer\ObserverforAddCustomVariable" />
        </event>
    </config>

4 - Create ObserverforAddCustomVariable.php file in app\code\[Vendor]\[Namespace]\Observer

<?php

    namespace [Vendor]\[Namespace]\Observer;

    use Magento\Customer\Api\CustomerRepositoryInterface;

    class ObserverforAddCustomVariable implements ObserverInterface
    {
        protected $customerRepository;
        public function __construct(
            CustomerRepositoryInterface $customerRepository
        ) {
            $this->customerRepository = $customerRepository;
        }
        public function execute(\Magento\Framework\Event\Observer $observer)
        {
            /** @var \Magento\Framework\App\Action\Action $controller */
            $transport = $observer->getEvent()->getTransport();
            if($transport->getOrder() != null)
            {
                $customer = $this->customerRepository->getById($transport->getOrder()->getCustomerId());
                if ($customer->getCustomAttribute('username')) {
                    $transport['username'] = $customer->getCustomAttribute('username')->getValue();
                }

            }
        }
    }

You can use custom Email variable in email template like “{var username}”