Mutipart/form-data to JSON in Node.js using Busboy - node.js

Question

I am working on an ios app which sends images and text to my firebase server using mutipart/form-data URLRequest. In order to process the data in my cloud function, I am using the method mentioned in documentation to parse the mutipart/form-data into JSON format, and here is my code:
const Busboy = require('busboy');
exports.test = functions.https.onRequest((req, res) => {
console.log("start");
console.log(req.rawBody.toString());
if (req.method === 'POST') {
var busboy = new Busboy({ headers: req.headers});
busboy.on('field', (fieldname, val, fieldnameTruncated, valTruncated, encoding, mimetype) => {
console.log('field');
});
busboy.on('finish', function() {
console.log('finish');
res.json({
data: null,
error: null
});
});
req.pipe(busboy);
} else {
console.log('else...');
}
});
However, the above code doesn't seem to work, and here is the output from console:
Function execution started
start
--Boundary-43F22E06-B123-4575-A7A3-6C144C213D09
Content-Disposition: form-data; name="json"
{"name":"Alex","age":"24","friends":["John","Tom","Sam"]}
--Boundary-43F22E06-B123-4575-A7A3-6C144C213D09--
finish
Function execution took 517 ms, finished with status code: 200
As you can see, the on('field') function never execute. What did I miss?
Also, here is the code in swift for sending httpRequest:
var request = URLRequest(url: myCloudFunctionURL)
request.httpMethod = "POST"
request.setValue("multipart/form-data; boundary=myBoundary", forHTTPHeaderField: "Content-Type")
request.addValue(userToken, forHTTPHeaderField: "Authorization")
request.httpBody = myHttpBody
let session = URLSession.shared
session.dataTask(with: request) { (data, response, requestError) in
// callback
}.resume()

Answer 1

You will have to call busboy.end(req.rawBody); instead of req.pipe(busboy) as described in the example of the documentation. I dont know why .pipe doesnt work. Calling .end will produce the same result but with a different way.
const Busboy = require('busboy');
exports.helloWorld = functions.https.onRequest((req, res) => {
const busboy = new Busboy({ headers: req.headers });
let formData = {};
busboy.on('field', (fieldname, val, fieldnameTruncated, valTruncated, encoding, mimetype) => {
// We're just going to capture the form data in a JSON document.
formData[fieldname] = val;
console.log('Field [' + fieldname + ']: value: ' + val)
});
busboy.on('finish', () => {
res.send(formData);
});
// The raw bytes of the upload will be in req.rawBody.
busboy.end(req.rawBody);
});

Answer 2

Enjoy this simple express middleware which converts all the Content-Type: multipart/form-data into you req.body in json format :)
const Busboy = require('busboy');
const expressJsMiddleware = (req, res, next) => {
const busboy = new Busboy({ headers: req.headers });
let formData = {};
busboy.on(
"field",
(fieldname, val, fieldnameTruncated, valTruncated, encoding, mimetype) => {
formData = { ...formData, [fieldname]: val };
},
);
busboy.on("finish", () => {
req.body = formData;
next();
});
req.pipe(busboy);
};