public function findWorkspaceRolesByUser(User $user, $executeQuery = true)
    {
        $dql = '
            SELECT r
            FROM Claroline\CoreBundle\Entity\Role r
            JOIN r.users u
            WHERE u = :user
            AND r.type = :type
            AND r.workspace IS NOT NULL
        ';

        $query = $this->_em->createQuery($dql);
        $query->setParameter('type', Role::WS_ROLE);
        $query->setParameter('user', $user);

        return $executeQuery ? $query->getResult() : $query;
    }