Sessions

Symfony provides a session object and several utilities that you can use to store information about the user between requests.

Configuration

Sessions are provided by the HttpFoundation component, which is included in all Symfony applications, no matter how you installed it. Before using the sessions, check their default configuration:

.. configuration-block::

    .. code-block:: yaml

        # config/packages/framework.yaml
        framework:
            # Enables session support. Note that the session will ONLY be started if you read or write from it.
            # Remove or comment this section to explicitly disable session support.
            session:
                # ID of the service used for session storage
                # NULL means that Symfony uses PHP default session mechanism
                handler_id: null
                # improves the security of the cookies used for sessions
                cookie_secure: auto
                cookie_samesite: lax
                storage_factory_id: session.storage.factory.native

    .. code-block:: xml

        <!-- config/packages/framework.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"
            xmlns:framework="http://symfony.com/schema/dic/symfony"
            xsi:schemaLocation="http://symfony.com/schema/dic/services
                https://symfony.com/schema/dic/services/services-1.0.xsd
                http://symfony.com/schema/dic/symfony https://symfony.com/schema/dic/symfony/symfony-1.0.xsd">

            <framework:config>
                <!--
                    Enables session support. Note that the session will ONLY be started if you read or write from it.
                    Remove or comment this section to explicitly disable session support.
                    handler-id: ID of the service used for session storage
                                NULL means that Symfony uses PHP default session mechanism
                    cookie-secure and cookie-samesite: improves the security of the cookies used for sessions
                -->
                <framework:session handler-id="null"
                                   cookie-secure="auto"
                                   cookie-samesite="lax"
                                   storage_factory_id="session.storage.factory.native"/>
            </framework:config>
        </container>

    .. code-block:: php

        // config/packages/framework.php
        use Symfony\Component\HttpFoundation\Cookie;
        use Symfony\Config\FrameworkConfig;

        return static function (FrameworkConfig $framework) {
            $framework->session()
                // Enables session support. Note that the session will ONLY be started if you read or write from it.
                // Remove or comment this section to explicitly disable session support.
                ->enabled(true)
                // ID of the service used for session storage
                // NULL means that Symfony uses PHP default session mechanism
                ->handlerId(null)
                // improves the security of the cookies used for sessions
                ->cookieSecure('auto')
                ->cookieSamesite(Cookie::SAMESITE_LAX)
                ->storageFactoryId('session.storage.factory.native')
            ;
        };

Setting the handler_id config option to null means that Symfony will use the native PHP session mechanism. The session metadata files will be stored outside of the Symfony application, in a directory controlled by PHP. Although this usually simplifies things, some session expiration related options may not work as expected if other applications that write to the same directory have short max lifetime settings.

If you prefer, you can use the session.handler.native_file service as handler_id to let Symfony manage the sessions itself. Another useful option is save_path, which defines the directory where Symfony will store the session metadata files:

.. configuration-block::

    .. code-block:: yaml

        # config/packages/framework.yaml
        framework:
            session:
                # ...
                handler_id: 'session.handler.native_file'
                save_path: '%kernel.project_dir%/var/sessions/%kernel.environment%'

    .. code-block:: xml

        <!-- config/packages/framework.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"
            xmlns:framework="http://symfony.com/schema/dic/symfony"
            xsi:schemaLocation="http://symfony.com/schema/dic/services
                https://symfony.com/schema/dic/services/services-1.0.xsd
                http://symfony.com/schema/dic/symfony https://symfony.com/schema/dic/symfony/symfony-1.0.xsd">

            <framework:config>
                <framework:session enabled="true"
                                   handler-id="session.handler.native_file"
                                   save-path="%kernel.project_dir%/var/sessions/%kernel.environment%"/>
            </framework:config>
        </container>

    .. code-block:: php

        // config/packages/framework.php
        use Symfony\Config\FrameworkConfig;

        return static function (FrameworkConfig $framework) {
            $framework->session()
                // ...
                ->handlerId('session.handler.native_file')
                ->savePath('%kernel.project_dir%/var/sessions/%kernel.environment%')
            ;
        };

Check out the Symfony config reference to learn more about the other available :ref:`Session configuration options <config-framework-session>`. You can also :doc:`store sessions in a database </session/database>`.

Basic Usage

The session is available through the Request object and the RequestStack service. Symfony injects the request_stack service in services and controllers if you type-hint an argument with :class:`Symfony\\Component\\HttpFoundation\\RequestStack`:

use Symfony\Component\HttpFoundation\RequestStack;

class SomeService
{
    private $requestStack;

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

    public function someMethod()
    {
        $session = $this->requestStack->getSession();

        // stores an attribute in the session for later reuse
        $session->set('attribute-name', 'attribute-value');

        // gets an attribute by name
        $foo = $session->get('foo');

        // the second argument is the value returned when the attribute doesn't exist
        $filters = $session->get('filters', []);

        // ...
    }
}

Stored attributes remain in the session for the remainder of that user's session. By default, session attributes are key-value pairs managed with the :class:`Symfony\\Component\\HttpFoundation\\Session\\Attribute\\AttributeBag` class.

Avoid Starting Sessions for Anonymous Users

Sessions are automatically started whenever you read, write or even check for the existence of data in the session. This may hurt your application performance because all users will receive a session cookie. In order to prevent that, you must completely avoid accessing the session.

More about Sessions

.. toctree::
    :maxdepth: 1

    session/database
    session/locale_sticky_session
    session/php_bridge
    session/proxy_examples
    session/configuring_ttl