The "chunk" argument must be of type string or an instance of Buffer

user_7387029 0
Viewed 59728

I'm running the following code and it fails with the below error.

AWS Code to list all objects inside a bucker

const http = require('http');
const host = '127.0.0.1';
const port = 5000;
const path = require('path')
const url = require('url')
const fs = require('fs')
var AWS = require('aws-sdk');



const laptopDate = JSON.parse(fs.readFileSync(`${__dirname}/data/data.json`, `utf-8`))

AWS.config.update({accessKeyId: '***', secretAccessKey: '***', region: 'ap-south-1'});
s3 = new AWS.S3({apiVersion: '2006-03-01'});

var params = { 
    Bucket: 'bucket-name'
}

const server = http.createServer(function(req, res){
    const path = url.parse(req.url, true).pathname
    const id = url.parse(req.url, true).query.id

    if (path === 'bucket' || path === '/')
      s3.listObjects(params, function (err, data) {
        if(err) throw err;
        res.writeHead(200, { 'Content-Type': 'text/html' });
        //const output = JSON.parse(data)
        console.log(data)
        res.end(data)
      });
});

server.listen(port, host, function(req, res) {
    console.log(`Server is listening on ${host} and ${port}`)

The first output which is console.log displays everything as expected. However the res.end to render the output to the screen fails with the below error.

The "chunk" argument must be of type string or an instance of Buffer. Received an instance of Object
    at ServerResponse.end (_http_outgoing.js:752:13)
    at Response.<anonymous> (D:\js\Extra\starter\index.js:30:13)
    at Request.<anonymous> (D:\js\Extra\starter\node_modules\aws-sdk\lib\request.js:364:18)
    at Request.callListeners (D:\js\Extra\starter\node_modules\aws-sdk\lib\sequential_executor.js:106:20)
    at Request.emit (D:\js\Extra\starter\node_modules\aws-sdk\lib\sequential_executor.js:78:10)
    at Request.emit (D:\js\Extra\starter\node_modules\aws-sdk\lib\request.js:683:14)
    at Request.transition (D:\js\Extra\starter\node_modules\aws-sdk\lib\request.js:22:10)
    at AcceptorStateMachine.runTo (D:\js\Extra\starter\node_modules\aws-sdk\lib\state_machine.js:14:12)
    at D:\js\Extra\starter\node_modules\aws-sdk\lib\state_machine.js:26:10
    at Request.<anonymous> (D:\js\Extra\starter\node_modules\aws-sdk\lib\request.js:38:9) {
  message: 'The "chunk" argument must be of type string or an instance of Buffer. Received an instance of Object',
  code: 'ERR_INVALID_ARG_TYPE',
  time: 2020-05-18T08:39:24.916Z
}
nodejs-server nodejs-stream aws-sdk-nodejs node.js javascript
3 Answers

Remove this res.writeHead(200, { 'Content-Type': 'text/html' });

And instead of res.end(data) use res.send(data) or better yet res.send({ data }).

EDIT I didn't notice that you didn't use express, try this:

res.writeHead(200, { 'Content-Type': 'application/json' });
res.write(JSON.stringify(data));
res.end();
user_72087000

In case this may help someone, try to use the objectMode propertie.

somthing like it

const t = new Transform({
    objectMode: true, // set this one to true
    transform(data, _, done) {
      //...your code
    }
  });
user_158988890

In case this may help someone, I was using data type other than String, Number to be exact, so I changed it to String to resolve this error

user_90968020
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