How to Add Custom Discount in Magento 2

Adding a custom discount in Magento 2 is one of the great marketing solutions you should set up at your Magento 2 store. Using a custom discount obviously, means you have to exclude a part of the price cart the customers must pay for. To offer the custom discount, this topic will guide you clearly when you work directly in the console. The below are four crucial steps you need to follow and complete the configuration of the custom discount in Magento 2.

4 steps to add custom discount in Magento 2

Step 1: Enter a total in the file sale.xml
Step 2: Set the value of discount
Step 3: Show the custom discount information in the layout file
Step 4: View model knockout

Step 1: Enter a total in the `sale.xml` file

The first thing you need to do is enterring a total in the sale.xml file. Please follow the path to find it: app/code/Mageplaza/HelloWorld/etc/sales.xml, then use the script:

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Sales:etc/sales.xsd">
 <section name="quote">
   <group name="totals">
     <item name="customer_discount" instance="Mageplaza\HelloWorld\Model\Total\Quote\Custom" sort_order="420"/>
   </group>
 </section>
</config>

Step 2: Set the value of discount

Determine and insert the amount of custom discount in the model app/code/Mageplaza/HelloWorld/Model/Total/Quote/Custom.php:

<?php
namespace Mageplaza\HelloWorld\Model\Total\Quote;
/**
* Class Custom
* @package Mageplaza\HelloWorld\Model\Total\Quote
*/
class Custom extends \Magento\Quote\Model\Quote\Address\Total\AbstractTotal
{
   /**
    * @var \Magento\Framework\Pricing\PriceCurrencyInterface
    */
   protected $_priceCurrency;
   /**
    * Custom constructor.
    * @param \Magento\Framework\Pricing\PriceCurrencyInterface $priceCurrency
    */
   public function __construct(
       \Magento\Framework\Pricing\PriceCurrencyInterface $priceCurrency
   ){
       $this->_priceCurrency = $priceCurrency;
   }
   /**
    * @param \Magento\Quote\Model\Quote $quote
    * @param \Magento\Quote\Api\Data\ShippingAssignmentInterface $shippingAssignment
    * @param \Magento\Quote\Model\Quote\Address\Total $total
    * @return $this|bool
    */
   public function collect(
       \Magento\Quote\Model\Quote $quote,
       \Magento\Quote\Api\Data\ShippingAssignmentInterface $shippingAssignment,
       \Magento\Quote\Model\Quote\Address\Total $total
   )
   {
       parent::collect($quote, $shippingAssignment, $total);
           $baseDiscount = 10;
           $discount =  $this->_priceCurrency->convert($baseDiscount);
           $total->addTotalAmount('customdiscount', -$discount);
           $total->addBaseTotalAmount('customdiscount', -$baseDiscount);
           $total->setBaseGrandTotal($total->getBaseGrandTotal() - $baseDiscount);
           $quote->setCustomDiscount(-$discount);
       return $this;
   }
}

Step 3: Show the custom discount information in the layout file

You have done with two above steps and the Grand Total has changed with the updated price, but your customers can’t see any information about the total discount. Thus, you should run the following command to add the total in the layout file app/code/Mageplaza/HelloWorld/view/frontend/layout/checkout_cart_index.xml from the console.

<?xml version="1.0"?>
<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
    <body>
       <referenceBlock name="checkout.cart.totals">
           <arguments>
               <argument name="jsLayout" xsi:type="array">
                   <item name="components" xsi:type="array">
                       <item name="block-totals" xsi:type="array">
                           <item name="children" xsi:type="array">
                               <item name="custom_discount" xsi:type="array">
                                   <item name="component"  xsi:type="string">Mageplaza_HelloWorld/js/view/checkout/summary/customdiscount</item>
                                   <item name="sortOrder" xsi:type="string">20</item>
                                   <item name="config" xsi:type="array">
                                       <item name="custom_discount" xsi:type="string" translate="true">Custom Discount</item>
                                   </item>
                               </item>
                           </item>
                       </item>
                   </item>
               </argument>
           </arguments>
       </referenceBlock>
   </body>
</page>

Step 4: View model knockout

To show the total, firstly call the model knockout app/code/Mageplaza/HelloWorld/view/frontend/web/js/view/checkout/summary/customdiscount.js with the code snippet:

define(
   [
       'jquery',
       'Magento_Checkout/js/view/summary/abstract-total'
   ],
   function ($,Component) {
       "use strict";
       return Component.extend({
           defaults: {
               template: 'Mageplaza_HelloWorld/checkout/summary/customdiscount'
           },
           isDisplayedCustomdiscount : function(){
               return true;
           },
           getCustomDiscount : function(){
               return '$10';
           }
       });
   }
);

Then get the total discount in the template knockout app/code/Mageplaza/HelloWorld/view/frontend/web/template/checkout/summary/customdiscount.html:

<!-- ko if: isDisplayedCustomdiscount() -->
<tr class="totals customdiscount excl">
   <th class="mark" colspan="1" scope="row" data-bind="text: custom_discount"></th>
   <td class="amount">
       <span class="price" data-bind="text: getCustomDiscount(), attr: {'data-th': custom_discount}"></span>
   </td>
</tr>
<!-- /ko -->

When you complete all steps, the custom discount will be immediately applied in the customer’s review cart with the name and the value of the custom discount. Using the custom price and giving them the better pricing are the good idea to boost your sales.

Related Topic

Final words

After following this tutorial, you will be able to add a custom discount to your Magento 2 store. This enables you to execute your sales campaigns easily. If you have any questions or want to discuss more this topic, please let us know.

Sam Nguyen

Sam is the CEO & co-founder of Mageplaza, a company established to support Magento merchants with different powerful tools and resources. Sam Nguyen is also the CEO & founder of Avada Commerce, an e-commerce solution provider headquartered in Singapore – aiming to support more than a million online businesses to grow and develop.

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