Magento 2 – Adding Custom Information to Checkout Order Summary

You will have to create a plugin for that. I wanted to add product flavor to order summary. This is the way I created a plugin and achieved what I wanted.

Vendor = Sejal

Files you need to create:

1. Registration.php : app\code\Sejal\Flavor\registration.php
2. di.xml : app\code\Sejal\Flavor\etc\di.xml
3. module.xml : app\code\Sejal\Flavor\etc\module.xml
4. ConfigProviderPlugin.php : app\code\Sejal\Flavor\Plugin\ConfigProviderPlugin.php
5. details.html : copy of vendor\magento\module-checkout\view\frontend\web\template\summary\item\details.html

you can override this file in your theme like this

app\design\frontend\Vendor\themename\Magento_Checkout\web\template\summary\item\details.html

Code: registration.php

<?php

\Magento\Framework\Component\ComponentRegistrar::register(
    \Magento\Framework\Component\ComponentRegistrar::MODULE,
    'Sejal_Flavor',
    __DIR__
);

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">
    <type name="Magento\Checkout\Model\DefaultConfigProvider">
        <plugin name="AddAttPlug" type="Sejal\Flavor\Plugin\ConfigProviderPlugin" />
    </type>
</config>

module.xml

<?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="Sejal_Flavor" setup_version="1.0.0">
    </module>
</config>

ConfigProviderPlugin.php

<?php

namespace Sejal\Flavor\Plugin;

class ConfigProviderPlugin extends \Magento\Framework\Model\AbstractModel
{

    public function afterGetConfig(\Magento\Checkout\Model\DefaultConfigProvider $subject, array $result)
    {

        $items = $result['totalsData']['items'];

        $objectManager = \Magento\Framework\App\ObjectManager::getInstance();
        for($i=0;$i<count($items);$i++){

            $quoteId = $items[$i]['item_id'];
            $quote = $objectManager->create('\Magento\Quote\Model\Quote\Item')->load($quoteId);
            $productId = $quote->getProductId();
            $product = $objectManager->create('\Magento\Catalog\Model\Product')->load($productId);
            $productFlavours = $product->getResource()->getAttribute('flavors')->getFrontend()->getValue($product);         
            if($productFlavours == 'No' || $productFlavours == 'NA'){
                $productFlavours = '';
            }
            $items[$i]['flavor'] = $productFlavours;
        }
        $result['totalsData']['items'] = $items;
        return $result;
    }

}

details.html

Copy vendor\magento\module-checkout\view\frontend\web\template\summary\item\details.html 

in theme and add

<div class="product-item-flavor" data-bind="text: $parent.flavor"></div>

below

<strong class="product-item-name" data-bind="text: $parent.name"></strong>

That's it! Hope it helps!

You can add additional options to order items using observer and it will show everywhere. First need to create events.xml for the observer:

<?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="catalog_product_load_after">
    <observer name="add_additional_option" instance="Namespace\Module\Observer\AddAdditionalOption"/>
</event>

After that write below code in observer file:

<?php
namespace Namespace\Module\Observer;

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

class AddAdditionalOption implements ObserverInterface
{

protected $_request;

public function __construct(
    RequestInterface $request
) {
    $this->_request = $request;
}

public function execute(\Magento\Framework\Event\Observer $observer)
{
    if ($this->_request->getFullActionName() == 'checkout_cart_add') {             
        $product = $observer->getProduct();
        $additionalOptions = [];
        $additionalOptions[] = array(
            'label' => "Custom Label",
            'value' => "Custom Info",
        );
        $observer->getProduct()->addCustomOption('additional_options', serialize($additionalOptions));
    }
}
}