protected function saveUser(Request $request)
 {
     $username = $request->request->get('username');
     $password = $request->request->get('password');
     $role = $request->request->get('role');
     if (!empty($username) && !empty($password) && !empty($role)) {
         if (User::exists($username)) {
             $this->addNotification('error', 'error.usernameAlreadyUsed');
             return $this->redirect('addUser');
         }
         if (!in_array($role, UserRole::$list)) {
             $this->abort(400, 'error.roleNotSpecified');
         }
         $user = new User(null, $username);
         $user->setRawPassword($password);
         $user->save();
         $userRole = new UserRole($user->getUserId(), $role);
         $userRole->save();
     } else {
         $this->addNotification('error', 'error.usernameOrPasswordEmpty');
         return $this->redirect('addUser');
     }
     return $this->redirect('listUsers');
 }