将 csv 文件从 s3 读入 ExcelJS 工作簿

Question

I want to do some operations on a csv file saved in s3 using exceljs library in my aws lambda. I am not able to initialize the exceljs Workbook object with the response returned by aws-sdk. As I explain below, the issue is mainly that the sdk gives stream of the MDN form whereas exceljs requires nodejs type of stream.

The sdk response is like this
const data: GetObjectCommandOutput = await s3Client.send(command)

data.Body is of type SdkStream<Readable | ReadableStream<any> | Blob | undefined> | undefined SdkStream<Readable | ReadableStream<any> | Blob | undefined> | undefined SdkStream<Readable | ReadableStream<any> | Blob | undefined> | undefined Here ReadableStream<any> is the MDN kind of stream.

I tried to create a nodejs stream like this(ignoring null check for now) const readableStream: ReadableStream = data.Body.;transformToWebStream();

const expectedNodejsStream = new Readable().wrap(readableStream);

But seems the issue here is wrap works for NodeJS .ReadableStream.

I also tried this as suggested in many answers

const nodeStream = new stream.Writable();
(data.Body!as Readable).pipe(nodeStream);

But an exception is thrown as data.Body does not get typecasted to Readable during runtime.

Exceljs constructor looks like this

const wb = new Excel.Workbook();
wb.xlsx.read(nodeStream);//doesnt work

or like this

new Excel.stream.xlsx.WorkbookReader(data.Body!.transformToWebStream());//does not work

Is it possible to create the excel workbook from sdk response data without having to convert the MDN stream to nodejs stream? If no, is there a way to do this conversion without implementing our own stream as suggested in this answer

aws-sdk/client-s3 v^3.121
aws-sdk v2.1158

Answer 1

data.Body can be typecasted to Buffer which is a nodejs construct. We can create a nodejs Readable stream from this buffer.

const data = await s3Client2.getObject(bucketParams).promise();
  console.log(`data: GetObjectCommandOutput`);
  const dataBuffer = Buffer.from(data.Body as Buffer);

  const wb = new Excel.Workbook();
  wb.csv.read(Readable.from(dataBuffer));