Getting a JSON object using node.js

Question

Im making a simple app to learn how node.js works. Using jquery and ajax i pass a JSON object to a node.js method. The problem is that i don't know how to get the specific JSON data in the node.js method.

client-side code:

 $(document).ready(function(){
 $('#guardarVehiculo').click(function(){
 var car = JSON.stringify(agregarCarro());
 $.ajax({
 type: 'POST',
 data: car,
 url: '/saveCar',
 dataType: 'JSON'
 }).done(function( response ) {
 console.log(response);
 });
 });
 });
 function addCar(){
 var id = getById('id').value;
 var brand = getById('brand').value;
 var model = getById('model').value;
 var transmission = getById('automatic').checked ? getById('automatico').value : getById('mechanic').value;
 var comment = getById('comment').value;
 var car = new Car(id, brand, model, transmission, comment);
 return car;
 }

node.js code:

var express = require('express');
var fs = require('fs');
var app = express();
app.get('/', function(req, res){
 res.sendFile(__dirname + "/index.html");
});
app.post('/saveCar', function(req, res){
 console.log(req);
});
var server = app.listen(8000, function(){
 var host = server.address().address;
 var port = server.address().port;
 console.log('Server running at: ' + host + ':' + port);
});

Thanks in advance.

• adeneo: If you're going to POST the data, you'll probably want a BodyParser that does this for you, otherwise GET data is easily available in req.query
• DCruz22: Thanks for the advice, now i know what to use un every case.

Answer 1

You could use the bodyParser middleware

var app = express();
var bodyParser = require("body-parser");
app.use(bodyParser.json());

and then req.body will contain the parsed JSON object:

app.post('/saveCar', function(req, res) {
 console.log(req.body);
});

There's just one gotcha. You need to set the proper Content-Type header when making the AJAX call so that the body parser knows that it should process JSON:

.ajax({
 type: 'POST',
 data: car,
 url: '/saveCar',
 contentType: 'application/json',
 dataType: 'JSON'
}).done(function( response ) {
 console.log(response);
});

• DCruz22: I was exactly looking for that. Thanks a lot!

Answer 2

Answer to understand flow.

JSON data posted from client is received in req.body.

req.body contains key-value pairs of data submitted in the request body. By default, it is undefined, and is populated when you use body-parsing middleware such as body-parser.

using body-parsing middleware to populate req.body as:

var app = express();
var bodyParser = require("body-parser");
app.use(bodyParser.json());

magic req.body will server JSON data, sent by client:

app.post('/save-car', function(req, res) {
 //hey! i am req.body and i have all data :)
});

• DCruz22: Thanks for the explanation!

Answer 3

Use BodyParser module.

Server:

var bodyParser = require("body-parser");
app.use(bodyParser.json());

Route:

cars{
 brand: "Tesla",
 model: "S-sport",
 color: "white"
}
app.post('/saveCar', function (req, res) {
 console.log(req.body);
 //to response back as Json.
 res.json(cars);
});