How to render json into a twig in Symfony2

The question is how to pass a json to twig to render a template. I’ve tried to pass a json with JsonResponse object but I did not find the way to render the template.

TarifasController.php

<?php

/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier <[e-mail]>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace AppBundleControllerAdmin;

use SymfonyComponentHttpFoundationRequest;
use SymfonyComponentHttpFoundationResponse;
use SymfonyComponentHttpFoundationJsonResponse;
use SymfonyBundleFrameworkBundleControllerController;
use SensioBundleFrameworkExtraBundleConfigurationMethod;
use SensioBundleFrameworkExtraBundleConfigurationRoute;
use SensioBundleFrameworkExtraBundleConfigurationSecurity;
use AppBundleEntityTarifa;

/**
 *
 * @Route("/tarifas")
 */
class TarifasController extends Controller
{

    /**
     * @Route("/", name="tarifa_index")
     */
    public function indexAction()
    {
        $entityManager = $this->getDoctrine()->getManager();
        $tarifas = $entityManager->getRepository('AppBundle:Tarifa')->findAll();

        return $this->render('admin/tarifas/index.html.twig', array('tarifas' => $tarifas));
        //return new JsonResponse(array('json_tarifas' => json_encode($tarifas)));

    }
}

index.html.twig

{% extends 'admin/layout.html.twig' %}

{% block body_id 'admin_post_show' %}

{% block main %}

    <h1>{{ 'label.project_list'|trans }}</h1>

    <table id="tarifas_index" class="table table-striped">
        <thead>
        <tr>
            <th>{{ 'Id' }}</th>
            <th><i class="fa fa-user"></i> {{ 'label.title'|trans }}</th>
            <th><i class="fa fa-calendar"></i> {{ 'label.summary'|trans }}</th>
            <th><i class="fa fa-calendar"></i> {{ 'label.content'|trans }}</th>
            <th><i class="fa fa-cogs"></i> {{ 'label.actions'|trans }}</th>
        </tr>
        </thead>
        <tbody>
        {% for tarifa in tarifas %}
            <tr>
                <td>{{ tarifa.id }}</td>
                <td>{{ tarifa.codigo }}</td>
                <td>{{ tarifa.nombre }}</td>
                <td>{{ tarifa.razon }}</td>
                <td>
                    <div class="item-actions">
                        <a href="{{ path('project_detail', { id: tarifa.id }) }}" class="btn btn-sm btn-default">
                            {{ 'action.show'|trans }}
                        </a>
                    </div>
                </td>
            </tr>
        {% endfor %}
        </tbody>
    </table>

    <script>
        $(document).ready( function () {
            $('#tarifas_index').DataTable({
                data: tarifas
            });
        } );
    </script>

{% endblock %}

How can I pass a json from the controller to use it in the DataTable (in twig template) but mantaining the render in this controller. Please, can you help me?

Answer

I don’t understand what you are trying to achieve but you can simply send json encoded and normal data to your twig, to use it how you want

return $this->render('admin/tarifas/index.html.twig', array(
    'tarifas' => $tarifas
    'json_tarifas' => json_encode($tarifas)
));