public function findDisplayableWorkspacesWithout(array $excludedWorkspaces)
    {
        $dql = '
            SELECT w
            FROM Claroline\CoreBundle\Entity\Workspace\Workspace w
            WHERE w.displayable = true
            AND w NOT IN (:excludedWorkspaces)
            ORDER BY w.name
        ';
        $query = $this->_em->createQuery($dql);
        $query->setParameter('excludedWorkspaces', $excludedWorkspaces);

        return $query->getResult();
    }