Scenario: Say you want to intercept a response from any WordPress API call before it gets returned to the user? For example, you want to block /users/ route or append additional content to a /posts/ response. Simply call the rest_pre_echo_response filter and you can modify all responses!

Demo

In our demo we are going to block all requests to the /users/ endpoint for those who aren’t logged in

Picture of Users Route Not Locked Down

All we have to do is create a callback function for the rest_pre_echo_response filter. And from there we can check $request->get_route() to get the route that is being requested. In this example we are simply returning our own output, however you can make additional query calls and simply modify the $results array if you want the original request to continue just modified with your changes with an array_merge.

<?php
/**
 * Plugin Name: Disable Users API
 * Description: Disables public access to the WordPress /wp/v2/users/* api routes.
 *
 * @author  Scott Anderson <[email protected]>
 * @package ThriftyDeveloper\MU_Plugin\SandBox\Diable_Users_API
 * @since   NEXT
 */

namespace ThriftyDeveloper\MU_Plugin\SandBox;

/**
 * Disables public access to the WordPress /wp/v2/users/* api routes.
 *
 * @author  Scott Anderson <[email protected]>
 * @since   NEXT
 *
 * @param array            $result  Results data from API request.
 * @param \WP_REST_Server  $server  Server instance.
 * @param \WP_Rest_Request $request Incoming Request.
 *
 * @return array
 */
function lockdown_users_api( array $result, \WP_REST_Server $server, \WP_Rest_Request $request ) : array {

	if( strpos( $request->get_route(), '/v2/users' ) !== false && ! is_user_logged_in() ) {
		return [
			'succes'  => false,
			'message' => __( 'You must be logged in to access /v2/users/* routes.', 'td-lockdown-users-api' ),
		];
	}

	return $result;
}

add_filter( 'rest_pre_echo_response', 'ThriftyDeveloper\MU_Plugin\SandBox\lockdown_users_api', 10, 3 );
Users api is now locked down.

Das It