How to forward a multipart/form-data POST request in Node to another service

问题

I need to send a multipart/form-data POST (xliff file) from the client to my Node.js server, and then capture the data in Node.js and forward that POST to another Java service.

I've used both multer and express-fileupload to parse the form-data stream and capture a Buffer of the xliff in Node.js and both gave me the file with its content as a buffer just fine.

However, I cannot seem to re-create a FormData object in the Node layer to forward the POST to the Java service.

I continue to get the error message "Connection terminated parsing multipart data" or just no response at all form the Java service.

I've Also attempted to use the tmp library to create a temporary file locally to write the buffer and then try to FormData('file', fs.createReadStream(<path>)), but that didn't seem to work for me either... though I'm not sure I was doing it correctly.

Using the exact same doPOST request directly form the Browser works fine, but once I try to capture the call in the Node layer and then forward the POST to the Java service, it doesn't work for me anymore.

const multer = require('multer');
const upload = multer();

router.post('/', upload.any(), (req, res) => {
  const { headers, files } = req;

  console.log('--------------- files:', files[0]); // object with buffer, etc.

  const XMLString = files[0].buffer.toString('utf8'); // xml string of the xliff

  const formFile = new FormData();
  formFile.append('file', XMLString);

  console.log('--------------- formFile:', formFile); // FormData object with a key of _streams: [<xml string with boundaries>, [Function: bound ]]

  headers['Content-Type'] = 'multipart/form-data';
  const url = 'some/url/to/Java/service'

  doPOST(url, formFile, {}, headers)
    .catch((error) => {
      const { status, data } = error.response;
      res.status(status).send(data);
    })
    .then(({ data }) => {
      res.send(data);
    });
});

回答1:

You can directly pass the buffer to your form data, but then you also need to specify the filename parameter.

const multer = require('multer');
const upload = multer();

router.post('/', upload.any(), (req, res) => {
  const { headers, files } = req;
  const { buffer, originalname: filename } = files[0];

  const formFile = new FormData();
  formFile.append('file', buffer, { filename });

  headers['Content-Type'] = 'multipart/form-data';
  const url = 'some/url/to/Java/service'

  doPOST(url, formFile, {}, headers)
    .catch((error) => {
      const { status, data } = error.response;
      res.status(status).send(data);
    })
    .then(({ data }) => {
      res.send(data);
    });
});

来源：https://stackoverflow.com/questions/53220350/how-to-forward-a-multipart-form-data-post-request-in-node-to-another-service

标签

node.js

post

form-data