Question

我正在尝试使用Typescript和aws-sdk软件包将文件上传到S3存储桶。理想的结果是：成功上传到s3，然后=>加载SQS消息。

这里是读取接收的文件并执行s3Upload的功能


        // on each byte of uploading
        file.on("data", function (data) {
            console.log("File [" + fieldname + "] got " + data.length + " bytes");
        });
        // whenever the upload is finished into this microservice
        file.on("end", function () {
            console.log("File [" + fieldname + "] Finished uploading");

        });
        const s3BucketLink = await saveToS3(filename, file);

### HERE IS IMPORTANT, I BASICALLY WANT TO CONFIRM THAT STATUS IS 200 and only then upload to SQS

        if (s3BucketLink.status === 200) {
            console.log("its done");
        }
        console.log("here");
        console.log(s3BucketLink);
    });

在我的saveToS3中，有这个


    interface S3Response {
        status: number;
        filepath: string;
    }

    export const saveToS3 = async (filename: string, file: any): Promise<S3Response> => {
        let status = {
            status: 400,
            filepath: ""
        };
        s3.listBuckets(function (err, data) {
            if (err) {
                console.log("Error", err);
            } else {
                console.log("Success", data.Buckets);
            }
        });

        const params = {
            Bucket: bucketName,
            Key: filename, // File name you want to save as in S3
            Body: file
        };
        s3.upload(params, function (err: Error, data: any) {
            if (err) {
                throw err;
            }
            console.log(`File uploaded successfully. ${data.Location}`);
            status = {
                status: 200,
                filepath: data.Location
            };

        });
        return status;


    };

我基本上是在尝试将状态设置为200，如果是这种情况，则继续并加载sqs。

console.log中的当前结果如下：

[Function]
File [File] got 65002 bytes
here
{ status: 400 }
File [File] got 65536 bytes
File [File] got 65536 bytes
File [File] got 65536 bytes
File [File] got 65536 bytes
File [File] got 65536 bytes
File [File] got 65536 bytes
File [File] got 65536 bytes
File [File] got 65536 bytes
File [File] got 65536 bytes
File [File] got 65536 bytes
File [File] got 43814 bytes
File [File] Finished uploading
Success [ { Name: 'name', CreationDate: 2020-05-31T06:50:22.000Z } ]
File uploaded successfully. https://name.s3.amazonaws.com/file_example_MP3_700KB.mp3

非常感谢您提供有关如何实现所需结果的帮助：）

Answer 1

您似乎在这里遇到了几个问题。

您正在执行几个异步方法（s3.listBuckets和s3.upload），而无需等待它们完成。因此，您要开始执行这些操作，然后调用return status;，这就是为什么您在文件上传完成之前提早获得该值的原因。您需要等待这些事情完成才能返回。

但是这两个方法都使用回调，而不是诺言，并且您希望saveToS3方法返回一个Promise。因此，您需要包装这两个方法调用。这是看起来像的简化示例（省略了一些代码）。在此示例中，该方法返回一个Promise，只有在触发s3.upload的回调时才解决，这意味着操作已完成或返回了错误。

export const saveToS3 = (filename: string, file: any): Promise<S3Response> => {
  return new Promise((resolve, reject) => {
    s3.upload(params, function (err: Error, data: any) {
      if (err) {
        return reject(err);
      }
      resolve(status);
    });
  });
}

这将导致任何await saveToS3()语句等待操作完成。

打字稿，等待功能

1 个答案: