expressions.rst

.. index::
   single: Expressions in the Framework

How to use Expressions in Security, Routing, Services, and Validation

Symfony comes with a powerful :doc:`ExpressionLanguage </components/expression_language>` component. It allows you to add highly customized logic inside configuration.

The Symfony Framework leverages expressions out of the box in the following ways:

• :doc:`Configuring services </service_container/expression_language>`;
• :doc:`Route matching conditions </routing/conditions>`;
• :ref:`Checking security <expressions-security>` (explained below) and :ref:`access controls with allow_if <security-allow-if>`;
• :doc:`Validation </reference/constraints/Expression>`.

For more information about how to create and work with expressions, see :doc:`/components/expression_language/syntax`.

Security: Complex Access Controls with Expressions

In addition to a role like ROLE_ADMIN, the isGranted() method also accepts an :class:`Symfony\\Component\\ExpressionLanguage\\Expression` object:

use Symfony\Component\ExpressionLanguage\Expression;
// ...

public function indexAction()
{
    $this->denyAccessUnlessGranted(new Expression(
        '"ROLE_ADMIN" in roles or (user and user.isSuperAdmin())'
    ));

    // ...
}

In this example, if the current user has ROLE_ADMIN or if the current user object's isSuperAdmin() method returns true, then access will be granted (note: your User object may not have an isSuperAdmin() method, that method is invented for this example).

This uses an expression and you can learn more about the expression language syntax, see :doc:`/components/expression_language/syntax`.

Inside the expression, you have access to a number of variables:

user

The user object (or the string anon if you're not authenticated).

roles

The array of roles the user has, including from the :ref:`role hierarchy <security-role-hierarchy>` but not including the IS_AUTHENTICATED_* attributes (see the functions below).

object

The object (if any) that's passed as the second argument to isGranted().

token

The token object.

trust_resolver

The :class:`Symfony\\Component\\Security\\Core\\Authentication\\AuthenticationTrustResolverInterface`, object: you'll probably use the is_*() functions below instead.

Additionally, you have access to a number of functions inside the expression:

is_authenticated

Returns true if the user is authenticated via "remember-me" or authenticated "fully" - i.e. returns true if the user is "logged in".

is_anonymous

Equal to using IS_AUTHENTICATED_ANONYMOUSLY with the isGranted() function.

is_remember_me

Similar, but not equal to IS_AUTHENTICATED_REMEMBERED, see below.

is_fully_authenticated

Similar, but not equal to IS_AUTHENTICATED_FULLY, see below.

has_role

Checks to see if the user has the given role - equivalent to an expression like 'ROLE_ADMIN' in roles.

is_remember_me is different than checking IS_AUTHENTICATED_REMEMBERED

The is_remember_me() and is_authenticated_fully() functions are similar to using IS_AUTHENTICATED_REMEMBERED and IS_AUTHENTICATED_FULLY with the isGranted() function - but they are not the same. The following shows the difference:

use Symfony\Component\ExpressionLanguage\Expression;
// ...

$ac = $this->get('security.authorization_checker');
$access1 = $ac->isGranted('IS_AUTHENTICATED_REMEMBERED');

$access2 = $ac->isGranted(new Expression(
    'is_remember_me() or is_fully_authenticated()'
));

Here, $access1 and $access2 will be the same value. Unlike the behavior of IS_AUTHENTICATED_REMEMBERED and IS_AUTHENTICATED_FULLY, the is_remember_me() function only returns true if the user is authenticated via a remember-me cookie and is_fully_authenticated only returns true if the user has actually logged in during this session (i.e. is full-fledged).

Learn more

• :doc:`/service_container/expression_language`
• :doc:`/reference/constraints/Expression`