Error writing to nodejs socket (TypeError: Invalid data, chunk must be a string or buffer, not object)

Question

Using electron I am trying to write out some bytes on a TCP socket. I am using Buffer.from to convert to buffer before calling write, but am still getting the above error. I have simplified it down to just creating an empty ArrayBuffer and calling Buffer.from

var abuff = new ArrayBuffer(8 + encodedBuffer.length);
console.log(Buffer.from(abuff));
socket.write(Buffer.from(abuff));

TypeError: Invalid data, chunk must be a string or buffer, not object The console.log shows the following:

Uint8Array(51) [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

and not Buffer?

Versions in electron: ares:"1.10.1-DEV" atom-shell:"1.7.9" chrome:"58.0.3029.110" electron:"1.7.9" http_parser:"2.7.0" modules:"54" node:"7.9.0" openssl:"1.0.2k" uv:"1.11.0" v8:"5.8.283.38" zlib:"1.2.11"

For anyone seeing this type of problem - This code was in the "renderer" process of Electron, the problem was the Buffer object in the "renderer" did not create a Buffer object from Buffer.from.

To solve I used IPC to send request from the renderer to the main process and let the main process manage the socket communication.

Grynets Grynets · Accepted Answer · 2018-01-02T20:00:11

As is said in error, chunk can be only type string or buffer.
So we have few solutions for your problem.
First one, just convert your object to string with JSON.stringify(<your data to send>), and than you can decode it on the other side.
Or you can use object mode, more here.

I've tried to test your code and it works.

var net = require('net');
var encodedBuffer = 9;
var abuff = new ArrayBuffer(8 + encodedBuffer.length);

var server = net.createServer(function(socket) {
  socket.write('Echo server\r\n');
  console.log(Buffer.from(abuff));
  socket.write(Buffer.from(abuff));
  socket.pipe(socket);
});

server.listen(1337, '127.0.0.1');

And when I start app and make request to server from another command line session nc 127.0.0.1 1337, I see output in server window.

Error writing to nodejs socket (TypeError: Invalid data, chunk must be a string or buffer, not object)

3 Answers