Creating Your Own Expression Function¶

Even though the built-in expressions allow you to do a lot already, there are cases where you want to add a custom expression function.

Let?s assume that you want to check that a user has a certain IP, you could do that using this expression container.get("request").getIp() == "127.0.0.1". However, if you duplicate this on several actions, it becomes a lot to write. Also, what happens if you want to add another IP? You would have to edit all the places where this expression is used. So instead of the above expression, let?s add another function isLocalUser() which you can use in your expressions.

<?php

namespace Acme\DemoBundle\Security;

use Symfony\Component\DependencyInjection\ContainerInterface;
use JMS\DiExtraBundle\Annotation as DI;

/** @DI\Service */
class RequestAccessEvaluator
{
    private $container;

    /**
     * @DI\InjectParams({
     *     "container" = @DI\Inject("service_container"),
     * })
     */
    public function __construct(ContainerInterface $container)
    {
        $this->container = $container;
    }

    /** @DI\SecurityFunction("isLocalUser") */
    public function isLocalUser()
    {
        return $this->container->get('request')->getClientIp() === '127.0.0.1';
    }
}