yii\rbac\DbManager::assign PHP Method

    public function assign($role, $userId)
    {
        $assignment = new Assignment(['userId' => $userId, 'roleName' => $role->name, 'createdAt' => time()]);
        $this->db->createCommand()->insert($this->assignmentTable, ['user_id' => $assignment->userId, 'item_name' => $assignment->roleName, 'created_at' => $assignment->createdAt])->execute();
        return $assignment;
    }

 public function assign($role, $userId)
 {
     if (!Users::findOne([Users::primaryKey()[0] => $userId])) {
         throw new Exception("Пользователь не найден");
     }
     return parent::assign($role, $userId);
 }