How to use extension_attributes in Magento2

Question

Is there anyone that can give me an example on how to use extension_attributes in Magento2?

Answer 1

Suppose we create an order delivery date, when the customer select shipping then the customer can select a delivery date. So you can create a extension attribute for \Magento\Checkout\Api\Data\ShippingInformationInterface in following way

<?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\Checkout\Api\Data\ShippingInformationInterface">
        <attribute code="delivery_date" type="string"/>
    </extension_attributes>
</config>

So now you can access this value when you using \Magento\Checkout\Api\Data\ShippingInformationInterface as di.

So in that case Magento\Checkout\Model\ShippingInformationManagement this class use \Magento\Checkout\Api\Data\ShippingInformationInterface as a params for saveAddressInformation method. So you can access following way:

$extAttributes = $addressInformation->getExtensionAttributes();
$deliveryDate = $extAttributes->getDeliveryDate();

For more details(Magento 2 Official Documentation)

Here is an example:

extension_attributes

Pick Extension Attributes value

[Update]

You can set extension_attributes by setExtensionAttributes method. Following class is an example: Click Here