WordPress :: Request to REST API from PHP

request-rest-api.php

<?php

// send data trough REST API
$request = new WP_REST_Request( 'POST', '/wp/v2/custom_post_type' );
$request->set_header( 'content-type', 'application/json' );
$request->set_body( wp_json_encode( $order_data ) );

// get response
$response 	   = rest_do_request( $request );
$response_data = $response->get_data();

// if error response
if ( $response->is_error() ) {
	$error 	 = $response->as_error();
	$message = $error->get_error_message();
	$status  = isset( $error_data['status'] ) ? $error_data['status'] : 500;
	wp_die( sprintf( __( 'An error occurred: %s (%d)', 'xyz' ), $message, $status ), __( 'Error!', 'xyz' ), array(
		'back_link' => true,
	) );
}