How to configure Symfony2 sticky locale during session

Question

I would like to translate my website thanks to an link on the right top.

I found out that, since Symfony 2.1, the locale is not stored in the session anymore.

So, I followed this Symfony documentation: Making the Locale "Sticky" during a User's Session

...Bundle/Service/LocaleListener.php

class LocaleListener implements EventSubscriberInterface
{
    private $defaultLocale;

    public function __construct($defaultLocale)
    {
        $this->defaultLocale = $defaultLocale;
    }

    public function onKernelRequest(GetResponseEvent $event)
    {

        $request = $event->getRequest();
        if (!$request->hasPreviousSession()) {
              return;
        }

        $locale = $request->attributes->get('_locale');
        var_dump($locale);

        if ($locale) {
             $request->getSession()->set('_locale', $locale);
        } else {
            $request->setLocale($request->getSession()->get('_locale', $this->defaultLocale));
        }
    }

    static public function getSubscribedEvents()
    {
        return array(
            // must be registered before the default Locale listener
            KernelEvents::REQUEST => array(array('onKernelRequest', 17)),
        );
    }
}

...Bundle/Resources/config/services.yml

locale_listener:
    class: ..Bundle\Service\LocaleListener
    arguments: ["%kernel.default_locale%"]
    tags:
        - { name: kernel.event_subscriber }   

./app/config/config.yml

framework:
    translator:      { fallback: en }

And, I add two links to translate my website on the parent twig template, shown below (Symfony2 locale languages whole page event listener).

base.html.twig

<li><a href="{{-
                path(app.request.get('_route'),
                app.request.get('_route_params')|merge({'_locale' : 'fr'}))
            -}}">FR</a></li>
<li><a href="{{-
                path(app.request.get('_route'),
                app.request.get('_route_params')|merge({'_locale' : 'en'}))
            -}}">EN</a></li>

Problem and Question

When I click on one of these links, the parameter _locale is added.

For instance:

satisfaction?_locale=fr

So, the value of the _locale parameter is fr. Consequently, my website should be translated in french.

Nevertheless, that

var_dump($locale)

in the listener is displayed three times:

1. null

2. en

3. null I don't understand why the _locale parameter is not found when it display null and why the en?

Answer 1

With your listener, you will catch all request and subrequest that is not needed. This explain the three times apparition.

Try to add this following code to your onKernelRequest method:

if (HttpKernel::MASTER_REQUEST != $event->getRequestType()) {
    return;
}

This will avoid subRequests and possibly resolve your problem.