WC REST and Webhook Processes
Overview
In this section, we’ll take a look at, what–exactly happens with REST API calls and Webhook events.
For each scenario we’ll show the process, discuss the architecture a bit, and then provide an overview on some of the basic avenues developers have for customizing the behavior of each of these processes
If you prefer, you can jump to the Knowledge check to see what you already know
WC REST Process
- WC links Authentication with the get_current_user functionThis is how WooCommerce identifies a user, without setting cookies
- WC REST ControllersThese are located in the includes/rest-api/Controllers folder of woocommerce are at the very heart of processing the REST API request.
Rest Controllers
- WC REST Controllers descend from the WordPress WP_Rest_Controller class and build on an abstract WC_REST_Controller classNote: there is a bit of an error in the Docs on this one, currently the class is not located in the ‘includes/abstracts folder’ but is in the includes/rest-api/Controllers/V3 folder instead
- The Controllers are organized into V1, V2, V3 directories, and linked with namespaces accordingly
- However, you should note, that it is not unusual for a class in Version1 to inherit properties from a foundational class in Version3
- Controllers are linked with specific endpoints in the Server.phpfound in the includes/rest-api folder file
WC REST Family Tree
Some REST Customization
The CRUD and Post controllers allow you to customize the parameters returnedWe’ll examine this more when we connect to an MRP system for a given collection
‘woocommerce_rest_api_get_rest_namespaces’ filter allows you to assign custom ControllersWe’ll examine this more when we connect to a mobile app to endpoints
protected function get_rest_namespaces() {
return apply_filters(
'woocommerce_rest_api_get_rest_namespaces',
[
'wc/v1' => $this->get_v1_controllers(),
'wc/v2' => $this->get_v2_controllers(),
'wc/v3' => $this->get_v3_controllers(),
]
);
}add_filter( 'determine_current_user', 'my_authenticator_function', 20 );return apply_filters( "rest_{$this->post_type}_collection_params", $params, $this->post_type );The Webhook Process
It’s a long road to processing a Webhook, with each webhook loaded on WC()->init, enqueuing itself, firing, queuing, and processing the client’s response
Some Webhook Customization
The WC_Webhook_Data_Store is responsible for loading all webhooks when WC initializes. By creating a custom data store, you can implement custom logic to determine which data stores will be loaded.
return apply_filters( 'woocommerce_webhook_payload', $payload, $resource, $resource_id, $this->get_id() );The ‘woocommerce_webhook_payload’ filter allows you to customize what dataRemember that the basis for the payload is the REST API version selected during webhook setup. is sent
do_action( 'woocommerce_webhook_delivery', $http_args, $response, $duration, $arg, $this->get_id() );The ‘woocommerce_webhook_delivery’ action allows you to process the responseConsider using HMAC with your application’s response, then cribbing the
WC_Rest_Authentication methods to authorize 
function wc_load_webhooks( $status = '', $limit = null ) {
$data_store = WC_Data_Store::load( 'webhook' );
$webhooks = $data_store->get_webhooks_ids( $status );
$loaded = 0;
...Conclusion
Now you have an understanding of exactly how the REST API and Webhooks interact with third party clients and a general overview of how you can customize their behavior.
Keep in mind that the brief lists of customizations are by no means comprehensiveAre they ever?. To learn more, you should have a look at the resources and inspect the code for other actions and filters available to you.
Up next we’ll look at two solid use cases on implementing the REST API and Webhooks:
But first, check your knowledge.
- woocommerce/class-wc-rest-authentication.php
- woocommerce/Server.php
- woocommerce/class-wc-rest-controller.php
- woocommerce/class-wc-rest-crud-controller.php
- woocommerce/class-wc-rest-shipping-zones-controller-base.php
- woocommerce/class-wc-rest-terms-controller.php
- woocommerce/class-woocommerce.php
- woocommerce/wc-webhook-functions.php
- woocommerce/class-wc-webhook.php
- woocommerce/class-wc-webhook-data-store.php
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