我如何访问golang中的错误个别属性

Question

！！ 我是 go 的新手！！

我正在使用数据同步 API 开始执行任务，没有任何问题。 我正在努力处理返回的错误结构，我想访问单个元素，但我似乎无法这样做。

例如在以下错误中我希望能够访问Message_的内容

2022/03/19 09:33:48 Sync called : 
InvalidRequestException: Unable to queue the task execution for task task-xxxxxxxxxxxx. The task already has another task execution exec-030b4a31dc2e33641 currently running or queued with identical Include and Exclude filter patterns. Please provide unique Include and Exclude filter patterns for the new task execution and try again.
{
  RespMetadata: {
    StatusCode: 400,
    RequestID: "xxxxxxxxxxxxxxxxxxxxx"
  },
  ErrorCode: "DedupeFailed",
  Message_: "Unable to queue the task execution for task task-xxxxxxxxxx. The task already has another task execution exec-xxxxxxxxxx currently running or queued with identical Include and Exclude filter patterns. Please provide unique Include and Exclude filter patterns for the new task execution and try again."
}

这是我的工作示例：

    // Create datasync service client
    svc := datasync.New(sess)

    params := &datasync.StartTaskExecutionInput{
        TaskArn : aws.String("arn:aws:datasync:*******************************"),
    }

    // start task execution
    resp, err := svc.StartTaskExecution(params)

    //err = req.Send()

    if err == nil { // resp is now filled
        fmt.Println(resp)  // this outputs this { TaskExecutionArn: "arn:aws:datasync:xxxxxxxx:task/task-03ecb7728e984e36a/execution/exec-xxxxxxxxxx" }

    } else {
        fmt.Println(err)
        //fmt.Println(err.Message()) THIS DOES NOT WORK
        //fmt.Println(err.Message_)  THIS ALSO DOES NOT WORK
    }

如果我这样做fmt.Println(err.Message())或this fmt.Println(err.Message_)我得到这个error err.Message undefined (type error has no field or method Message) err.Message_ undefined (type error has no field or method Message_)

我go哪里错了？

Answer 1

Go 的 AWS SDK 中的错误通常是接口awserr.Error （代码为 Github ）。

如果你只想收到消息，你可以这样做：

resp, err := svc.StartTaskExecution(params)

if err != nil {
    if awsErr, ok := err.(awserr.Error); ok {
        fmt.Println(awsErr.Message())
    } else {
        fmt.Println(err.Error())
    }
}

首先，检查是否确实存在错误：

if err != nil {...}

然后，我们尝试将错误转换为它的特定“类型” awserr.Error ：

err.(awserr.Error)

cast 的返回值是特定的错误awsErr和一个bool来指示 cast 是否有效（ ok ）。

awsErr, ok := err.(awserr.Error)

代码的 rest 基本上只是检查，如果ok == true ，如果是这种情况，您可以访问Message之类的错误字段：

if awsErr, ok := err.(awserr.Error); ok {
    fmt.Println(awsErr.Message())
}

否则，您只需打印标准的 Go 错误消息：

if awsErr, ok := err.(awserr.Error); ok {
    ...
} else {
    fmt.Println(err.Error())
}