Service in symfony2 - how service file should look like? - symfony

Question

I am trying to create service in symfony2 which will verify if session contains certain information and if not redirect the user to another controller. I want this piece of code to work as a service as I will be using it in many controllers.
I have problem as manual on Symfony2 book does not provide information how service file should look like. Should it be a normal php class?
Please find below dump of my files with information on error that I receive.
In \AppBundle\Services I create file my_isbookchosencheck.php containing:
<?php
namespace AppBundle\my_isbookchosencheck;
class my_isbookchosencheck
{
public function __construct();
{
$session = new Session();
$session->getFlashBag()->add('msg', 'No book choosen. Redirected to proper form');
if(!$session->get("App_Books_Chosen_Lp")) return new RedirectResponse($this->generateUrl('app_listbooks'));
}
}
My service.yml:
my_isbookchosencheck:
class: AppBundle\Services\my_isbookchosencheck
My conntroller file:
/**
* This code is aimed at checking if the book is choseen and therefore whether any further works may be carried out
*/
$checker = $this->get('my_isbookchosencheck');
Error:
FileLoaderLoadException in FileLoader.php line 125: There is no extension able to load the configuration for "my_isbookchosencheck" (in C:/wamp/www/symfony_learn/app/config\services.yml). Looked for namespace "my_isbookchosencheck", found "framework", "security", "twig", "monolog", "swiftmailer", "assetic", "doctrine", "sensio_framework_extra", "fos_user", "knp_paginator", "genemu_form", "debug", "acme_demo", "web_profiler", "sensio_distribution" in C:/wamp/www/symfony_learn/app/config\services.yml (which is being imported from "C:/wamp/www/symfony_learn/app/config\config.yml").

Answer 1

There are few mistakes that you made, which I am going to explain in short, and I will give you an example of the service you want to create.
You created your service in AppBundle\Services, yet your namespace is registered differently - namespace AppBundle\Services\my_isbookchosencheck;. It should be namespace AppBundle\Services;. I would also advise you to use singular names when creating directories - in this case Service would be better, instead of Services.
You're using your __constructor directly to apply some logic and return the result of it. Better way would be to create a custom method, which could be accessed when necessary.
You're creating new instance of Session which means that you wont be able to access anything that was previously added and stored in session. The right way here, would be to inject RequestStack which holds the current Request and get the session from there.
I believe you also registered your service wrong. In your services.yml file, it should be under services: option. This is why you got the error you pasted.
So, let's see how your service should like.
services.yml
services:
book_service:
class: AppBundle\Service\BookService
arguments:
- #request_stack
- #router
BookService.php
namespace AppBundle\Service;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\RequestStack;
use Symfony\Component\Routing\RouterInterface;
class BookService {
/* #var $request Request */
private $request;
/* #var $router RouterInterface */
private $router;
public function __construct(RequestStack $requestStack, RouterInterface $router) {
$this->request = $requestStack->getCurrentRequest();
$this->router = $router;
}
public function isBookChoosen() {
$session = $this->request->getSession();
// Now you can access session the proper way.
// If anything was added in session from your controller
// you can access it here as well.
// Apply your logic here and use $this->router->generate()
}
}
Now in your controller you can simply use it like this:
$this->get('book_service')->isBookChoosen()
Well this is a short example, but I hope you got the idea.

Answer 2

try
services:
my_isbookchosencheck:
class: AppBundle\Services\my_isbookchosencheck
in your services.yml, and check that you use the correct namespaces.
Your Class is fine and it should work, however may i suggest that you use
symfony2 session service instead of creating the session object yourself, you can pass it as a constructor argument:
<?php
// namespace edited
namespace AppBundle\Services;
use Symfony\Component\HttpFoundation\Session\Session;
class my_isbookchosencheck
{
public function __construct(Session $session);
{
$session->getFlashBag()->add('msg', 'No book choosen. Redirected to proper form');
if(!$session->get("App_Books_Chosen_Lp")) return new RedirectResponse($this->generateUrl('app_listbooks'));
}
}
and then edit your services.yml accordingly, so the service container will inject the session object:
services:
my_isbookchosencheck:
class: AppBundle\Services\my_isbookchosencheck
arguments: [#session]
Also check out his question on so:
How do you access a users session from a service in Symfony2?

Answer 3

Services are just regular PHP classes, nothing special. But you must register it in order to be recognized by the system. Here are the steps how you do it,
Create a regular PHP class (you can inject other services if it requires)
namespace Acme\DemoBundle\Service;
class MyService
{
private $session;
public function _construct(SessionInterface $session /* here we're injecting the session service which implements the SessionInterface */)
{
$this->session = $session;
}
// other methods go here, which holds the business logic of this class
}
ok, we created a class, we need to register it to be able to use it by service container, here how you do it:
the simplest way is to put it into config.yml file, like this:
services:
my_service:
class: Acme\DemoBundle\Service\MyService
arguments:
- #session
or, another way, is to create a file (e.g. services.yml, may be in config folder), and import it inside the config.yml file (the content of the file is the same as the first way):
imports:
- { resource: services.yml }
or, you can create a services.yml(the content of the file is the same as the first way) file inside you bundle's Resources folder, specify it under the load method of your Extension class (under the DependencyInjection folder), (this way requires some special directory and file structure, read about it in the doc):
class AcmeDemoExtension extends Extension
{
public function load(array $configs, ContainerBuilder $container)
{
$loader = new YamlFileLoader($container, new FileLocator(__DIR__ . '/../Resources'));
$loader->load('services.yml');
}
}
In you case, you're not registering your service, the service container just couldn't find it. Register it by one of the above ways.