Magento 2.x.x extension attributes API add object array

Question

Have added custom attribute to order API with following info here: https://www.atwix.com/magento-2/adding-custom-attribute-to-api-response-in-magento-2/

It adds the "customer_feedback": "this is my feedback" fine to api.

How to add an Json object array ? E.G:

"my_custom_object": {
    "Key1": "value!",
    "Key2": "value2"
}

Thanks

Answer 1

I sourced out the answer to my question!.

One simple cannot do:

$my_custom_object = array("Key1" => "value!") 
OR
$my_custom_object = json_encode(array("Key1" => "value!"));

It expect the value to be an object: So setting customAttribute like so:

$extensionAttributes->setOurCustomData($ourCustomData);

$ourCustomData Must be an object: So I create Interface with getter and setter and a model that implements the interface and in extension_attributes.xml:

...
<attribute code="our_custom_data" type="Vendor\Module\Api\Data\CustomInterface"/>
...

In Plugin orderRepository:

Inject model : \Vendor\Module\Model\CustomModel $customModel

...
$ourCustomData = $this->customModel;
$extensionAttributes->setOurCustomData($ourCustomData);
...

Hope it helps anyone!