管道流从busboy请求发布

Question

I have multipart/form-data that I am posting to an express endpoint /data/upload , form markup below:

form(enctype="multipart/form-data", action="/data/upload", method="post")
  input(type="file", name="data")

I'm using busboy to read the file stream, which is working fine. From there, I want to send the stream again as multipart/form-data to a second Java backend, using the request npm module. JS client/Java server code below:

  req.busboy.on('file', function (fieldName, fileStream, fileName, encoding, mimeType) {

    var reqBody = {
      url: server.baseURL + 'api/data',
      headers: {
        'Connection': 'keep-alive',
        'Content-Type': 'multipart/form-data'
      },
      formData: {
        file: fileStream
      }
    };

    request.post(reqBody, function (err, r, body) {
      // Do rendering stuff, handle callback
    });
 });

Java endpoint (api/data)

@POST
@Consumes(MediaType.MULTIPART_FORM_DATA)
public void addData(FormDataMultiPart formDataMultiPart) {
  // Handle multipart data here      
}

I don't think I'm sending the file correctly as multipart/form-data here... but I'm having a hard time figuring out how to essentially pipe the stream from busboy directly to request without reading/writing from a temp file on the client-side. Any ideas?

Java stack trace:

Apr 27, 2016 5:07:12 PM org.glassfish.jersey.filter.LoggingFilter log
INFO: 3 * Server has received a request on thread qtp1631904921-24
3 > POST http://localhost:8080/api/data
3 > Connection: keep-alive
3 > Content-Length: 199
3 > Content-Type: multipart/form-data; boundary=--------------------------331473417509479560313628
3 > Host: localhost:8080

Apr 27, 2016 5:07:12 PM org.glassfish.jersey.filter.LoggingFilter log
INFO: 3 * Server responded with a response on thread qtp1631904921-24
3 < 400

17:07:13.003 [qtp1631904921-24] WARN  org.eclipse.jetty.http.HttpParser parseNext - bad HTTP parsed: 400 No URI for HttpChannelOverHttp@425137da{r=1,c=false,a=IDLE,uri=null}

Rahat's recommended change :

 31     var reqBody = {
 32       url: server.baseURL + 'data',
 33       headers: {
 34         'Connection': 'keep-alive',
 35         'Content-Type': 'multipart/form-data'
 36       }
 37     };
 38 
 39     req.pipe(req.busboy.pipe(request.post(reqBody)));

Threw error:

Error: Cannot pipe. Not readable.
   at Busboy.Writable.pipe (_stream_writable.js:154:22)

Answer 1

The problem here is that you need to provide 'Content-Length' for the multipart upload manually, because request (and underlying form-data ) can't figure it out by themselves. So request sends invalid Content-Length: 199 (the same for any incoming file size), which breaks the java multipart parser.

There are multiple workarounds:

1) Use incoming request 'Content-Length'

request.post({
  url: server.baseURL + 'api/data',
  formData: {
    file: {
      value: fileStream,
      options: {
        knownLength: req.headers['content-length']
      }
    }
  }
}, function (err, r, body) {
  // Do rendering stuff, handle callback
})

This will produce a bit incorrect request though, because incoming length includes other upload fields and boundaries, but busboy was able to parse it w/o any complaints

2) Wait until file is completely buffered by the node app then send it to java

var concat = require('concat-stream')
req.busboy.on('file', function (fieldName, fileStream, fileName, encoding, mimeType) {
  fileStream.pipe(concat(function (fileBuffer) {
    request.post({
      url: server.baseURL + 'api/data',
      formData: {
        file: fileBuffer
      }
    }, function (err, r, body) {
      // Do rendering stuff, handle callback
    })
  }))
})

This will increase app memory consumption, so you needed to be careful and consider using busboy limits

3) Buffer file to disk before uploading (just for the reference)

• express + multer - I recommend using express for webservers, it makes things more manageable, and multer is based on the busboy
• formidable

Answer 2

If possible, send a custom header with exactly size file (bytes). The header always can be read before handle payload stream. Use this instead of content-length header of previous answer, because that sometimes doesn't works (with small files, i guess, but i cannot ensure that works with large files).

Answer 3

For the answer of Afanasii Kurakin

request.post({
  url: server.baseURL + 'api/data',
  formData: {
    file: {
      value: fileStream,
      options: {
        knownLength: req.headers['content-length']
      }
    }
  }
}, function (err, r, body) {
  // Do rendering stuff, handle callback
})

You should change from req.headers['content-length'] to the real file size, normally the content-length from header is bigger than the file size. I got pain because of the content-length and after using the file size, everything worked perfectly.