Error: Data after transformation must be a string, an Array Buffer, a Buffer, or a Stream

Question

I am getting this error while using POST method with axios and formidable. I am trying to upload a file to an API URL. Here is my code snippet.

var server = http.createServer(function(req, response) {
var filePath = '.';
filePath += req.url;


var mimeType = {
    '.ico': 'image/x-icon',
    '.html': 'text/html',
    '.js': 'text/javascript',
    '.json': 'application/json',
    '.css': 'text/css',
    '.png': 'image/png',
    '.jpg': 'image/jpeg',
    '.wav': 'audio/wav',
    '.mp3': 'audio/mpeg',
    '.svg': 'image/svg+xml',
    '.pdf': 'application/pdf',
    '.doc': 'application/msword',
    '.eot': 'appliaction/vnd.ms-fontobject',
    '.ttf': 'aplication/font-sfnt'
};

if (filePath == './') {
    filePath += "templates/index.html"
}

if (filePath == './success') {
    filePath = "templates/success.html"
}
var postUrl = "https://example.com/345678934/attachments";
const form = formidable({ multiples: true , keepExtensions : true});
const option = {
    method:'post',
    url: postUrl,
    headers : {
        'content-type': 'application/json'
    }
}

axios.post(option, function(err, fields,files) {
    console.log("error from post: ",err)
    //response.writeHead(200, {'content-type': 'application/json'});
    response.end(JSON.stringify({ fields, files }, null, 2));
    console.log("Upload completed");
    console.log(files);


}).then(res => {
    console.log(`statusCode: ${res.status}`)
    console.log(res)
  })
  .catch(error => {
    console.error("error from catch",error)
  })

fs.readFile(filePath, function(error, content) {
    if (error) {
        if (error.code == 'ENOENT') {
            response.writeHead(404);
            response.end('Page not Found');
        } else {
            response.writeHead(500);
            response.end('Internal error: ' + error.code);
        }
    } else {
        var extname = path.extname(filePath);
        response.writeHead(200, {
            'Content-Type': mimeType[extname] || 'text/plain'
        });
        response.end(content, 'utf-8');
    }
});

});

server.on('listening', function(err) {
    if (err) throw err;
    console.log(Date() + ' Server is running...');
});

server.listen(7000);

Here I am expecting to upload all types of file extension and multiple files also can be uploaded to that API URL.

Here it's throwing an exception "error from catch Error: Data after transformation must be a string, an ArrayBuffer, a Buffer, or a Stream"

Answer 1

I had a similar error using FormData on NestJS Application, I don't know if this helps you but to solve my problem i did the following changes:

import * as FormData from 'form-data';
import { Readable } from 'stream';

const form = new FormData();
form.append('file', Readable.from(file.buffer), {
      filename: file.originalname,
    })

credits to: https://stackoverflow.com/a/70660823/12216924