public function cast()
 {
     return Actor::find_cast_for($this->id);
 }
<?php

require_once "../includes/initialize.php";
// require key and id parameter.
if (empty($_GET['id']) || empty($_GET['key'])) {
    sendResponse(400, "Invalid request. Please provide \"ID\" and \"key\" parameters.");
} else {
    if ($_GET['key'] != API_KEY) {
        sendResponse(403, "Invalid API key.");
    } else {
        $cast = export_arr(Actor::find_cast_for($_GET['id']));
        sendResponse(200, json_encode($cast));
    }
}