Symfony2 : Handling error on a single controller - web-services

Question

I made a controller to provide some webservices in JSON and i would like to provide some errors informations when Symfony throw an exception ( Error 500 ) , how can i write such a thing ?
The main purpose of the webservice is to update informations in Symfony DB provided by the caller in POST values.
in my controller i return response in JSON and i would like to handle Symfony exception ( like when the values provided or not fitting the schema designed ) to return details informations about errors .
i thought about making a test of every values but it would be a long time to write and not e easy code to read or using a try / catch system , but i think Symfony already provide such a function .
What do you think ?
Thx :)

Answer 1

I think you should use an EventListener to catch errors and return the proper response.
You can place it inside your SomethingBundle/EventListener folder and also you need to define a service in order to be loaded by Symfony.
More info: Event Listener
I hope I helped you, if you think I might be wrong, let me know. Good luck!
EDIT
If you only want to catch the errors inside a specific controller (for example) a controller called Webservice inside your SomethingBundle, you must check it before doing anything:
public function onKernelException(GetResponseForExceptionEvent $event)
{
$request = $event->getRequest();
if($this->getBundle($request) == "Something" && $this->getController($request) == "Webservice")
{
// Do your magic
//...
}
}
private function getBundle(Request $request)
{
$pattern = "#([a-zA-Z]*)Bundle#";
$matches = array();
preg_match($pattern, $request->get('_controller'), $matches);
return (count($matches)) ? $matches[0] : null;
}
private function getController(Request $request)
{
$pattern = "#Controller\\\([a-zA-Z]*)Controller#";
$matches = array();
preg_match($pattern, $request->get('_controller'), $matches);
return (count($matches)) ? $matches[1] : null;
}
DANGER This code is not tested, is only an approach for you to build your own code. But, if I have something wrong on it, tell me. I'd like to keep my examples clean.

Answer 2

Use JsonResponse Symfony class in sandbox:
use Symfony\Component\HttpFoundation\JsonResponse;
$data = array(); // array of returned response, which encode to JSON
$data['error_message'] = 'Bad request or your other error...');
$response = new JsonResponse($data, 500); // 500 - response status
return $response;