Node.js how to read json data from request?

Question

I have a server as following:

app.post('/', function(req, res, next) {
   console.log(req);
   res.json({ message: 'pppppppppppppssssssssssssss ' });   
});

The request is sent from a client as:

$.ajax({
    type: "POST",
    url: self.serverURI,
    data: JSON.stringify({ "a": "128", "b": "7" }),
    dataType: 'json',
    success: function (result) {
        console.log(result);
    },
    error: function (xhr, ajaxOptions, thrownError) {
        console.log(xhr);
    }
});

so far the connection fine.

My problem is in the server:

console.log(req);

where I want to read the data I sent. How can I read { "a": "128", "b": "7" } from req?

Solution 1

Although you're not mentioning it, your code looks like it's written for an Express environment. My answer is targeted to this.

Make sure to use body-parser for Express. In case, your project depends on some generated boilerplate code, it's most likely already included in your main server script. If not:

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

Installation with npm: npm install body-parser --save

The parsed JSON can then be accessed through req.body:

app.post('/', function(req, res, next) {
    console.log(req.body); // not a string, but your parsed JSON data
    console.log(req.body.a); // etc.
    // ...
});

Solution 2

For Express 4+,

const express = require("express");
const app = express();

app.use(express.json());

Then, you can use req.body as expected.

app.post("/api", (req, res) => {
  /*
    If the post request included { data: "foo" },
    then you would access `data` like so:
  */
  req.body.data
  ...
});

Comments

[arslan]

Thank you so much, it worked. Finally ufffffff. It would be great if you could explain how can I send such a JSon to client by "res" parameter :)

[qqilihq]

res.json(object) is the correct way to go. As already given in your sample code.

[arslan]

I read many tutorials. Some use "res.json(object)", some use "res.end(something)", quite confusing for people who new to this.

[qqilihq]

res.json will automatically set the response content-type header to application/json, while res.send will set text/html by default. If you're returning JSON, definitely use the res.json function.

[qqilihq]

More details here: stackoverflow.com/questions/19041837/…

[arslan]

I am trying to send a large data as JSon, is there any example of constructing JSon data and send back? I think I need to define a function for construct JSon and send by "res.json(data)". Could you show me an example of it? I would appreciate it

[qqilihq]

To keep things here on topic, rather open a new post for this. I can have a look later on :)

[arslan]

I try myself first, then ask if have troubles :) thx, you helped a lot

[Tomáš Zato]

Well is that really something that can't be solved without external library?