Content length: 0 in a json response Symfony2 - symfony

Question

Always i get a blank, i have a action in my controller like this
/**
* #Route("/check/{key}.json", defaults={"_format"="json"})
* #Template()
*/
public function processAction($upload_key)
{
/* make thing */
return array('data' => $process_data);
}
in my process.json.twig file i have
{% set res = { 'data': data } %}
{{ res | json_enconde | raw }}
other form
{{ { 'data': data } | json_enconde | raw }}
i've try this too:
{{ 'hello' | json_encode | raw }}
in chrome i get this response:
Connection:close
Content-Length:0
Content-Type:application/json
Date:Mon, 19 Dec 2011 05:13:17 GMT
Server:Apache/2.2.20 (Ubuntu)
X-Powered-By:PHP/5.3.6-13ubuntu3.3
and get nothing from the server, i cant solve this

Answer 1

There are two ways to achieve this, it depends on which you prefer and whether or not your action is supposed to support multiple _format types.
Option A - An action that only returns JSON
You can bypass the template completely.
In your controller remove the #Template annotation and instead return new Response(json_encode($process_data));
Option B - An action that supports different formats OR you just wish to render the JSON in a template
By an action that renders different formats I refer to an action with a route as so:
#Route("/check/{key}.{_format}", defaults={"_format"="json"}
#Template
Although a controller in this question goes down the route of "an action that only supports JSON but you want to render it in a template".
Assuming the controller's processAction returns return array('data' => $process_data); as the question asks then rendering this as JSON inside a template called process.json.twig should be done as follows {{ data|json_encode }}, there is no need to pre-process data or turn it into another array or anything like that inside the template.