FixtureMenu.php

<?php

namespace My\CustomBundle;

use Doctrine\Common\DataFixtures\FixtureInterface;
use Doctrine\Common\Persistence\ObjectManager;
use Symfony\Component\DependencyInjection\ContainerAware;

class FixtureMenu  extends ContainerAware implements FixtureInterface
{
    public function load(ObjectManager $objectManager)
    {
        $factory = $this->container->get('ktw_database_menu.factory');

        $menu = $factory->createItem('root');
        $menu->setChildrenAttribute('class', 'main-nav nav navbar-nav');

        $menu->addChild('Home', array('route' => 'homepage'));
        $menu->addChild('Page 1', array('route' => 'page1'));
        $menu->addChild('Page 2', array('route' => 'page2'));

        $objectManager->persist($menu);
        $objectManager->flush();
    }
}