Capture exceptions with a different handler for applications REST

Question

The problem

I'm building a small application with Silex. It's divided between a REST application and a website. (two controllers, same app). The website has installed its own custom error handler, which returns a user friendly html page. The problem is that in the part dedicated REST application, I should somehow handle exceptions to return type [json] and content different from the error handler's custom website.

With Symfony2

This argument can also be applied to Symfony2, I would like also possible solution for it!

A first solution for Silex

Wrap the methods in try-catch block in order to rethrowing the exception to handler.

$app->get('/api/show-list', function() use($app){
    try {
        $show = // db query, etc.
        return $app->json(array('show' => $show), 200);
    } catch (Exception $e) {
        throw new MyException;
    }
});

$app->error(function (MyException $e, $code) {
    // error api
});

The issue is that if an exception is thrown out of my controllor the default error handler will be used. Some tips? And with Symfony?

You could create your own exception class that has other variables, one of which you could use to indicate whether to return json or not, then just have one error handler that checks the value and does the appropriate response. — gunnx
Do you have any code for MyException Class that you can add to the question? — gunnx
@gunnx, I mean, where in the flow of my request I should include an hypothetical MyException::isJsonError — Federkun
Did you try actually returning a response from your custom error function? As I believe it will try other handlers until one of them returns something. — gunnx

Thomas Trötscher Thomas Trötscher · Accepted Answer · 2013-03-04T10:03:39

I have been using the following in my Silex RESTful app to return errors in json format:

$app->error(function (\Exception $e, $code) use($app) {
    return $app->json(array("error" => $e->getMessage()),$code);    
});

Not sure if this is the right way, but it works for me.

This is documented on the Silex site: http://silex.sensiolabs.org/doc/usage.html#error-handlers

Capture exceptions with a different handler for applications REST

The problem

With Symfony2

A first solution for Silex

2 Answers