I followed this guide to add a custom product attribute to quote and sales order item throughout the order process and this works fine.

My custom attribute is added to the sales_order_item table correctly but will not return in the order api call: /rest/V1/orders/X . The item in the order are present but the custom added attribute seems to be missing.

How do I add this sales_order_item attribute to the API output?

I tried it by adding a "extension_attributes.xml" to my custom module (that included the custom attribute: see earlier mentioned link) but that seems to have no effect:

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    <extension_attributes for="Magento\Sales\Api\Data\OrderItemInterface">
        <attribute code="deliverycode" type="string" />

Thanks for the help!


Still haven't resolved the issues after trying some minor things. I ran into this topic, which is closely related to my issue. I am trying to adjust the code to suit my needs but I haven't found the answer yet after a few hours of trying to switch the code the be suitable for "sales_order_item". If anyone has any solutions or tips to push me in the right direction they are very much appreciated!



Please try to get the order item rest/V1/orders/items/(orderid)

Or else add extension attributes in order api

1. create Vendor\Module\etc\extension_attributes.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Api/etc/extension_attributes.xsd">
<extension_attributes for="Magento\Sales\Api\Data\OrderInterface">
    <attribute code="order_attribute" type="string" />

Then create observer for event ‘sales_order_load_after’

2. Vendor\Module\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="sales_order_load_after">
    <observer name="sales_order_load_order_attribute" instance="Vendor\Module\Observer\Sales\OrderLoadAfter" />

Create a file to get the event data

3. vendor\Module\Observer\Sales\OrderLoadAfter.php

namespace Vendor\Module\Observer\Sales;
use Magento\Framework\Event\ObserverInterface;
class OrderLoadAfter implements ObserverInterface
public function execute(\Magento\Framework\Event\Observer $observer)
    $order = $observer->getOrder();
    $extensionAttributes = $order->getExtensionAttributes();
    if ($extensionAttributes === null) {
        $extensionAttributes = $this->getOrderExtensionDependency();
    $attr = `Get the order item attributes`
private function getOrderExtensionDependency()
    $orderExtension = \Magento\Framework\App\ObjectManager::getInstance()->get(
    return $orderExtension;

Please run the upgrade, compile and deploy command


  • Hi, I am trying your suggestions, thanks! I think your code above relates to extending the ORDERS instead of the ORDER ITEMS that have a custom attribute (sales_order_items) am I correct in assuming so? I am trying to rewrite for it, no luck yet though. – JohnRP Jul 30 at 13:35
  • Yes, We add the custom attribute in order. Probably, we can not add in the order_item directly. YOu need to use the order extension attributes to achieve that. – Moin Malek Jul 30 at 13:42
  • I do not quite understand. So in order to add my custom sales_order_item attribute to the API I will need to use an order extension instead of an order item extension (OrderItemInterface)? Thanks! – JohnRP Jul 30 at 13:49
  • I looked into your code a bit further and I thank you for your effort, but I need to expose the custom sales_order_item attribute to the api and not a custom sales_order attribute. I am still looking into it, if I find a way I will post an update. – JohnRP Jul 31 at 17:49

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