public function get_assignable_roles_for_json($otherusers = false) {
        $rolesarray = array();
        $assignable = $this->get_assignable_roles($otherusers);
        foreach ($assignable as $id => $role) {
            $rolesarray[] = array('id' => $id, 'name' => $role);
        }
        return $rolesarray;
    }