[json] How do I consume the JSON POST data in an Express application

I'm sending the following JSON string to my server.

(
        {
        id = 1;
        name = foo;
    },
        {
        id = 2;
        name = bar;
    }
)

On the server I have this.

app.post('/', function(request, response) {

    console.log("Got response: " + response.statusCode);

    response.on('data', function(chunk) {
        queryResponse+=chunk;
        console.log('data');
    });

    response.on('end', function(){
        console.log('end');
    });
});

When I send the string, it shows that I got a 200 response, but those other two methods never run. Why is that?

const express = require('express');_x000D_
let app = express();_x000D_
app.use(express.json());

This app.use(express.json) will now let you read the incoming post JSON object

A beginner's mistake...i was using app.use(express.json()); in a local module instead of the main file (entry point).

For those getting an empty object in req.body

I had forgotten to set headers: {"Content-Type": "application/json"} in the request. Changing it solved the problem.

Sometimes you don't need third party libraries to parse JSON from text. Sometimes all you need it the following JS command, try it first:

        const res_data = JSON.parse(body);

For Express v4+

install body-parser from the npm.

$ npm install body-parser

https://www.npmjs.org/package/body-parser#installation

var express    = require('express')
var bodyParser = require('body-parser')

var app = express()

// parse application/json
app.use(bodyParser.json())

app.use(function (req, res, next) {
  console.log(req.body) // populated!
  next()
})

@Daniel Thompson mentions that he had forgotten to add {"Content-Type": "application/json"} in the request. He was able to change the request, however, changing requests is not always possible (we are working on the server here).

In my case I needed to force content-type: text/plain to be parsed as json.

If you cannot change the content-type of the request, try using the following code:

app.use(express.json({type: '*/*'}));

Instead of using express.json() globally, I prefer to apply it only where needed, for instance in a POST request:

app.post('/mypost', express.json({type: '*/*'}), (req, res) => {
  // echo json
  res.json(req.body);
});