How to use session in Symfony

Question

I\'m getting a hard time trying to understand how symfony session works.
And couldn\'t find the answer I\'m looking for here on S.O. or other external sources.

[SETT

Answer 1

Well, first a big thanks to Gopal Joshi who helped me figure out a lot of things... :)

For those who come later, read his answer, it's helpful in a lot of ways...
I would also suggest reading this question, it goes in pair with the current question.

Meanwhile, I came out with this:

1: Register the service

AppBundle\Resources\config\services.yml

app.session_handler:
    class: SalonBundle\Services\SessionHandler
    arguments:
        - "@doctrine"
        - "@router"
    tags:
        - { name: kernel.event_listener, event: kernel.request, method: setSession }

First, I will point that I use the argument @router, but unless you need to redirect the response to another url, it's not needed.

2: Create the service

AppBundle\EventListener\SessionHandler.php

doctrine=$doctrine;
        $this->router=$router;
    }

    public function setSession(GetResponseEvent $responseEvent) {
        //This function parameter call on GetResponseEvent class
        //for the same reason as above.
        $site=$this->doctrine->getRepository('AppBundle:Site')->findOneBy(array('url'=>$responseEvent->getRequest()->getSchemeAndHttpHost()));
        if($site) {
            $session=$responseEvent->getRequest()->getSession();
            $session->clear();
            $session->set('site', $site);
        } else {
            if($responseEvent->getRequest()->get('_route') != 'some_route') {
                //This next line is the only reason as to why we pass "@router" as argument
                $responseEvent->setResponse(new RedirectResponse($this->router->generate('some_route')));
            }
        }
    }
}

To sum things up, it's very close to Gopal Joshi answer...
In fact, it's the same, just with some code cleanup...
Both his answer and mine are working...
The only difference is that mine won't show warning like:
Method 'methodName()' not found or import 'import\path\and\name' is never used

Gopal Joshi, if you happen to read my answer, I'm asking you, which one should I validate?
Being honest here, most of the credits is yours, so I will validate the answer you want... ;)