<?php
namespace D\FormBundle\Controller;

use Symfony\Bundle\FrameworkBundle\Controller\Controller;
use Symfony\Component\HttpFoundation\Response;

class MyAjaxController extends Controller
{
    public function indexAction()
    {
        return $this->render('DFormBundle:Default:form.html.twig');
    }

    public function updateDataAction(){
         $request = $this->get('request');
         $data1 = $request->query->get('country');


        //handle data

        //prepare the response, e.g.
        $response = array("code" => 100, "success" => true);
        //you can return result as JSON
        return new Response(json_encode($response));
    }
}