Add custom fields to an event

Your custom module might generate data that would be useful to insert into an existing Commerce event. Processors allow you to enrich the data contained in an event before it is transmitted to the eventing service. You can optionally assign a priority to each processor. The priority is important in cases when changes from one processor can affect the logic of another processor, or when processors add a new element with the same key.

You must configure a module's io_events.xml or root app/etc/io_events.xml file to add custom fields. You cannot declare them in the system config.php file or add them using the CLI.

Configure the `io_events.xml` file

The <processors> element defines the processors that inject custom data into the specified event. This element contains one or more <processor> elements, which can contain the following attributes:

Attribute	Required	Description
`class`	Yes	The fully-qualified class name.
`priority`	No	An integer indicating the order in which multiple processors are executed. The system executes unprioritized processors first, in the order listed. All processors with defined priority values are executed in numerical order, from lowest to highest.

The following example adds the order_status, order_id, and order_details fields to the observer.sales_order_save_after event payload. The assigned priority values indicate the processors will be executed in the following order:

TestProcessorOrderStatus
TestProcessorOrderDetails
TestProcessorOrderId

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module-commerce-events-client/etc/io_events.xsd">
    <event name="observer.sales_order_save_after">
        <fields>
            <field name="entity_id" />
            <field name="base_currency_code" />
            <field name="shipping_method" />
        </fields>
        <processors>
            <processor class="Magento\AdobeCommerceEventsClient\Event\TestProcessorOrderStatus" priority="10"/>
            <processor class="Magento\AdobeCommerceEventsClient\Event\TestProcessorOrderId" priority="30"/>
            <processor class="Magento\AdobeCommerceEventsClient\Event\TestProcessorOrderDetails" priority="20"/>
        </processors>
    </event>
</config>
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<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module-commerce-events-client/etc/io_events.xsd">
    <event name="observer.sales_order_save_after">
        <fields>
            <field name="entity_id" />
            <field name="base_currency_code" />
            <field name="shipping_method" />
        </fields>
        <processors>
            <processor class="Magento\AdobeCommerceEventsClient\Event\TestProcessorOrderStatus" priority="10"/>
            <processor class="Magento\AdobeCommerceEventsClient\Event\TestProcessorOrderId" priority="30"/>
            <processor class="Magento\AdobeCommerceEventsClient\Event\TestProcessorOrderDetails" priority="20"/>
        </processors>
    </event>
</config>

The event payload will be similar to the following:

{
    "value": {
       "entity_id": "3",
       "base_currency_code": "USD",
       "shipping_method": "tablerate_bestway",
       "order_status": "1", 
       "order_details": "test details",
       "order_id": "3"
  }
}
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{
    "value": {
       "entity_id": "3",
       "base_currency_code": "USD",
       "shipping_method": "tablerate_bestway",
       "order_status": "1", 
       "order_details": "test details",
       "order_id": "3"
  }
}

Processor definitions

The processor class must implement EventDataProcessorInterface. This interface contains the process method, which accepts the following arguments. It returns an array.

public function process(Event $event, array $eventData): array

You must create a separate class for each field to be added.

In the following example, the TestProcessorOrderStatus class adds the order_status field and a value to the eventData array.

<?php
/**
 * Copyright [first year code created] Adobe
 * All rights reserved.
 */
declare(strict_types=1);

namespace Magento\AdobeCommerceEventsClient\Event;

use Magento\AdobeCommerceEventsClient\Event\Processor\EventDataProcessorInterface;

class TestProcessorOrderStatus implements EventDataProcessorInterface
{
    public function process(Event $event, array $eventData): array
    {
        $eventData['order_status'] = 1;
        return $eventData;
    }
}
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<?php
/**
 * Copyright [first year code created] Adobe
 * All rights reserved.
 */
declare(strict_types=1);
namespace Magento\AdobeCommerceEventsClient\Event;
use Magento\AdobeCommerceEventsClient\Event\Processor\EventDataProcessorInterface;
class TestProcessorOrderStatus implements EventDataProcessorInterface
{
    public function process(Event $event, array $eventData): array
    {
        $eventData['order_status'] = 1;
        return $eventData;
    }
}