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Nov 12, 2013
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[#2956] Refactoring the scopes entry #2972

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c5ae3dd
[#2956] Refactoring the scopes entry entirely to not talk about the r…
weaverryan Sep 12, 2013
d417f7b
[#2972] Many small tweaks - thanks very much to @WouterJ and @xabbuh
weaverryan Nov 12, 2013
3dcbbc2
[#2972] Clarifying how to use the request_stack with an example
weaverryan Nov 12, 2013
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95 changes: 81 additions & 14 deletions book/service_container.rst
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Expand Up @@ -754,28 +754,95 @@ Injecting the dependency by the setter method just needs a change of syntax:
and "setter injection". The Symfony2 service container also supports
"property injection".

.. _book-container-request-stack:

Injecting the Request
~~~~~~~~~~~~~~~~~~~~~

.. versionadded:: 2.4
The ``request_stack`` service was introduced in version 2.4.

Almost all Symfony2 built-in services behave in the same way: a single
instance is created by the container which it returns whenever you get it or
when it is injected into another service. There is one exception in a standard
Symfony2 application: the ``request`` service.

If you try to inject the ``request`` into a service, you will probably receive
a
:class:`Symfony\\Component\\DependencyInjection\\Exception\\ScopeWideningInjectionException`
exception. That's because the ``request`` can **change** during the life-time
of a container (when a sub-request is created for instance).

As of Symfony 2.4, instead of injecting the ``request`` service, you should
inject the ``request_stack`` service instead and access the Request by calling
the ``getCurrentRequest()`` method. For earlier versions, or if you want to
understand this problem better, refer to the cookbook article
:doc:`/cookbook/service_container/scopes`.
the ``getCurrentRequest()`` method:

namespace Acme\HelloBundle\Newsletter;

use Symfony\Component\HttpFoundation\RequestStack;

class NewsletterManager
{
protected $requestStack;

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

public function anyMethod()
{
$request = $this->requestStack->getCurrentRequest();
// ... do something with the request
}

// ...
}

Now, just inject the ``request_stack``, which behaves like any normal service:

.. configuration-block::

.. code-block:: yaml

# src/Acme/HelloBundle/Resources/config/services.yml
services:
newsletter_manager:
class: "Acme\HelloBundle\Newsletter\NewsletterManager"
arguments: ["@request_stack"]

.. code-block:: xml

<!-- src/Acme/HelloBundle/Resources/config/services.xml -->
<?xml version="1.0" encoding="UTF-8" ?>
<container xmlns="http://symfony.com/schema/dic/services"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">

<services>
<service
id="newsletter_manager"
class="Acme\HelloBundle\Newsletter\NewsletterManager"
>
<argument type="service" id="request_stack"/>
</service>
</services>
</container>

.. code-block:: php

// src/Acme/HelloBundle/Resources/config/services.php
use Symfony\Component\DependencyInjection\Definition;
use Symfony\Component\DependencyInjection\Reference;

// ...
$container->setDefinition('newsletter_manager', new Definition(
'Acme\HelloBundle\Newsletter\NewsletterManager',
array(new Reference('request_stack'))
));

.. sidebar: Why not Inject the request Service?

Almost all Symfony2 built-in services behave in the same way: a single
instance is created by the container which it returns whenever you get it or
when it is injected into another service. There is one exception in a standard
Symfony2 application: the ``request`` service.

If you try to inject the ``request`` into a service, you will probably receive
a
:class:`Symfony\\Component\\DependencyInjection\\Exception\\ScopeWideningInjectionException`
exception. That's because the ``request`` can **change** during the life-time
of a container (when a sub-request is created for instance).


.. tip::

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