Mrthdrb

I have created a new custom order attribute named delivery_date and shown the same in sales order grid but i am not getting the custom attribute in my order Api response.

The error I am getting is Fatal error: Uncaught Error: Call to undefined method

MagentoSalesApiDataOrderExtension::setTipAndTrickAttribute() 

Please help.

app/code/Amos/CustomOrder/etc/di.xml

<?xml version="1.0"?>
<!--
/**
 * Copyright © 2013-2017 Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
-->
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../../../lib/internal/Magento/Framework/ObjectManager/etc/config.xsd">
 <virtualType name="MagentoSalesModelResourceModelOrderGrid" type="MagentoSalesModelResourceModelGrid">
 <arguments>
 <argument name="columns" xsi:type="array">
 <item name="delivery_date" xsi:type="string">sales_order.delivery_date</item>
 <item name="no_of_days" xsi:type="string">sales_order.no_of_days</item>
 <item name="no_of_crew" xsi:type="string">sales_order.no_of_crew</item>
 </argument>
 </arguments>
 </virtualType> 
</config>

app/code/Amos/CustomOrder/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_delivery_date" instance="MagestoreTipAndTrickObserverSalesOrderLoadAfter" />
</event>
</config>

Amos/CustomOrder/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="MagentoSalesApiDataOrderInterface">
 <attribute code="delivery_date" type="string" />
</extension_attributes>
</config> 

Amos/CustomOrder/Observer/Sales/OrderLoadAfter.php

<?php
namespace AmosCustomOrderObserverSales;
use MagentoFrameworkEventObserverInterface;
class OrderLoadAfter implements ObserverInterface

public function execute(MagentoFrameworkEventObserver $observer)

 $order = $observer->getOrder();
 $extensionAttributes = $order->getExtensionAttributes();
 if ($extensionAttributes === null) 
 $extensionAttributes = $this->getOrderExtensionDependency();
 
 $attr = $order->getData('delivery_date');
 $extensionAttributes->setTipAndTrickAttribute($attr);
 $order->setExtensionAttributes($extensionAttributes);

private function getOrderExtensionDependency()

 $orderExtension = MagentoFrameworkAppObjectManager::getInstance()->get(
 'MagentoSalesApiDataOrderExtension'
 );
 return $orderExtension;