Express.json not parsing POST body - undefined

Question

JSON POST data being received from an IoT API that I want to consume. Note the multipart form-data. Sometimes an image file can be attached, but I am not interested in processing the image part:

POST {
  host: '192.168.78.243:3000',
  accept: '*/*',
  'content-length': '1178',
  'content-type': 'multipart/form-data; boundary=------------------------f519f81dc2e1d562'
}
--------------------------f519f81dc2e1d562
Content-Disposition: form-data; name="event"; filename="event_3913.json"
Content-Type: application/octet-stream

{"packetCounter":"3913",
"capture_timestamp":"1600677267347",
"datetime":"20200921 204027000",
"stateUTF8":"ABC123",
"stateASCII":"ABC123",
.....

I want to access the JSON data, and are using express. As per this SO answer I have tried this approach with express.json():

const express = require('express');
const bodyParser = require('body-parser');

const app = express();

app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));

app.post('/test', (req, res) =>{
    if (req.method === 'POST') {
        console.log('POST request recd');
    }
    console.log(req.body);
    res.status(200).send('It works');
});

app.listen(3000, () => console.log('server started'));

However all I get on console is undefined {}.

UPDATE

Even with the correct imports the express/body-parser method does not work.

This method below works in so far as it proves a POST request is being received. But I need to use a express method so that I can access the incoming data:

let buffers = [];
const http =require('http')
http.createServer((request, response) => {
    console.log('Now we have a http message with headers but no data yet.');
    if (request.method === 'POST' && request.url === '/test') {
        console.log('Hit');
    }
    request.on('data', chunk => {
        console.log('A chunk of data has arrived: ', chunk);
        buffers.push(chunk);
    });
    request.on('end', () => {
        console.log('No more data');
        let body = Buffer.concat(buffers);
        console.log(String(body));
    })
}).listen(3000)

How do I get to the data with express?

You could use the body-parser middleware http://expressjs.com/en/resources/middleware/body-parser.html — BraveButter, Sep 21 '20 at 09:48
I have tried app.use(express.bodyParser()); and installed with npm install --save body-parser but I still get body-parser needs to be installed separately?? — Al Grant, Sep 21 '20 at 09:50
you also need to require it separately, it's not part of express — stranded, Sep 21 '20 at 10:00
You have mentioned that data coming from API looks like .... so I want to know are you hitting an api from the server or there is some frontend from which that data is coming to your server? (please elaborate about the purpose of your application) also, from Express version 4.16+ body parser is not requires — Nisha Dave, Sep 21 '20 at 10:07

Prathamesh More · Answer 1 · 2020-09-21T10:17:26.597

You installed body-parser but haven't imported body-parser in order to work.

const express = require('express');
const bodyParser = require('body-parser');

const app = express();

app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));

app.use(express.static('public'));

app.get('/', (req, res) => {
  res.sendFile('public/index.html');
}); 

app.post('/test', (req, res) =>{
  console.log(req.body);
  res.status(200).send('It works');
});

app.listen(3000, () => console.log('server started'));

Updated Answer

const express = require('express');
const bodyParser = require('body-parser');

const app = express();

app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));

app.use(express.static('public'));

app.get('/', (req, res) => {
  res.send(`<form action="/test" method="POST" >
  <label for="fname">First name:</label>
  <input type="text" id="fname" name="fname"><br><br>
  <label for="lname">Last name:</label>
  <input type="text" id="lname" name="lname"><br><br>
  <input type="submit" value="Submit">
</form>`)
}); 

app.post('/test', (req, res) =>{
  console.log(req.body);
  res.status(200).send('It works');
});

app.listen(3000, () => console.log('server started'));

Try it online https://repl.it/join/ldopaeji-pprathameshmore

there must be something different about the API data - because it is undefined with that POST data. — Al Grant, Sep 21 '20 at 10:21
Yes. Still {} - thats with a cut n paste minus your fake data method. — Al Grant, Sep 21 '20 at 10:24
Try this @AlGrant https://repl.it/join/ldopaeji-pprathameshmore — Prathamesh More, Sep 21 '20 at 10:24

Jerubaal Xerxes · Answer 2 · 2020-09-21T12:37:24.237

0

const express = require('express');
const bodyParser = require('body-parser');
const app = express();
app.use(express.json());
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));

app.post('192.168.78.243:3000/', (req,res) =>{
console.log(req.body.stateUTF8);
console.log(req.body);
res.sendStatus(200);
});
app.listen(3000, ()=> console.log('listening'));

Try this!!

edited Sep 21 '20 at 12:37

answered Sep 21 '20 at 10:34

Jerubaal Xerxes

61
7

do this after you have declarer the body-parser middleware as other answers suggest. – Jerubaal Xerxes Sep 21 '20 at 10:37
what is nametoserver in respect of my sample data? – Al Grant Sep 21 '20 at 10:41
Just showing that its that variable name that you will call on the server side "nametoserver" its on the leftside of the ':' you can give any name. – Jerubaal Xerxes Sep 21 '20 at 10:50

Express.json not parsing POST body - undefined

2 Answers2