Extender MenuBundle

MainMenu.php

<?php

namespace SFM\WebsiteBundle\Menu;

use Knp\Bundle\MenuBundle\Menu;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\Routing\Router;

class MainMenu extends Menu
{
    public function addChild($child, $uri = null, $attributes = array(), $class = null)
    {
        $child = parent::addChild($child, $uri, $attributes, $class);

        if ($child->getIsCurrent()) {
            return $child->setLinkAttribute('class', 'active');
        }

        return $child;
    }

    ...
}