in AppController.php add a method
public function json($data){
$this->response->type('json');
$this->response->body(json_encode($data));
return $this->response;
}
and in your ***Controller.php or any other controller
public function simpleAction() {
if (this->request->is('ajax') && this->request->is('post') ){
$res = [
'data' => [
/* your data */
]
];
return $this->json($res);
}
}