Returning rendered template as JSON with Symfony2 and Twig

gistfile1.php

class YourController extends Controller
{
   public function your_returnAction(){
        $lReturn = array();
        //use renderview instead of render, because renderview returns the rendered template
        $lReturn['html'] = $this->renderView('Bundle:Controller:yourtemplate.html.twig');

        return new Response(json_encode($lReturn), 200, array('Content-Type'=>'application/json'));
  }
}

use Symfony\Component\HttpFoundation\JsonResponse;

    {
        $page = $request->get('page');
        $from = $page * BlogPost::POST_PER_PAGE;

        $posts = $this->getDoctrine()->getRepository('AppBundle:BlogPost')->getPosts(BlogPost::POST_PER_PAGE, $from);

        if ($posts) {
            $result = $this->renderView('blog/index.html.twig', [
                'base_dir' => realpath($this->getParameter('kernel.project_dir')).DIRECTORY_SEPARATOR,
                'posts' => $posts,
            ]);

            return new JsonResponse(['success' => true, 'articles' => $result]);
        } else {
            return new JsonResponse(['success' => false, 'posts' => []]);
        }
    }