How to send a file inside a request in Node.js using the http(s) module?

Question

I need to send a file as part of a POST request in Node.js and I don't want to use other packages or external libraries but plain http (https) module, part of the standard Node.js API.

From the Node.js doc, an example

This example in the Node.js doc, hints about what I want to achieve:

const postData = querystring.stringify({'msg': 'Hello World!'});

const options = {
  hostname: 'http://localhost',
  port: 8080,
  path: '/upload',
  method: 'POST',
  headers: {
    'Content-Type': 'application/x-www-form-urlencoded',
    'Content-Length': Buffer.byteLength(postData)
  }
};

const req = http.request(options, (res) => {
  console.log(`STATUS: ${res.statusCode}`);
  console.log(`HEADERS: ${JSON.stringify(res.headers)}`);
  res.setEncoding('utf8');
  res.on('data', (chunk) => {
    console.log(`BODY: ${chunk}`);
  });
  res.on('end', () => {
    console.log('No more data in response.');
  });
});

req.on('error', (e) => {
  console.error(`problem with request: ${e.message}`);
});

// Write data to request body
req.write(postData);
req.end();

What I want

This example is very close to what I want to achieve, the only difference is in the very first lines:

const postData = querystring.stringify({'msg': 'Hello World!'}); // <== I want to send a file

Instead of sending a string, I want to send a file. The doc page says that it should be possible:

http.request() returns an instance of the http.ClientRequest class. The ClientRequest instance is a writable stream. If one needs to upload a file with a POST request, then write to the ClientRequest object.

How can I do this?

---

Attempts

I have tried:

clientRequest.write(fs.createReadStream("C:/Users/public/myfile.txt"));
clientRequest.end();

But I get this error:

TypeError [ERR_INVALID_ARG_TYPE]: The first argument must be one of type string or Buffer. Received type object

Answer 1

I'm not sure if you're using the streams correctly. Try this:

fs.createReadStream(filePath).pipe(req);