How to access the request body when POSTing using Node.js and Express?

Question

I have the following Node.js code:

var express = require('express');
var app = express.createServer(express.logger());
app.use(express.bodyParser());

app.post('/', function(request, response) {
    response.write(request.body.user);
    response.end();
});

Now if I POST something like:

curl -d user=Someone -H Accept:application/json --url http://localhost:5000

I get Someone as expected. Now, what if I want to get the full request body? I tried doing response.write(request.body) but Node.js throws an exception saying "first argument must be a string or Buffer" then goes to an "infinite loop" with an exception that says "Can't set headers after they are sent."; this also true even if I did var reqBody = request.body; and then writing response.write(reqBody).

What's the issue here?

Also, can I just get the raw request without using express.bodyParser()?

Answer 1

Starting from express v4.16 there is no need to require any additional modules, just use the built-in JSON middleware:

app.use(express.json())

Like this:

const express = require('express')

app.use(express.json())    // <==== parse request body as JSON

app.listen(8080)

app.post('/test', (req, res) => {
  res.json({requestBody: req.body})  // <==== req.body will be a parsed JSON object
})

Note - body-parser, on which this depends, is already included with express.

Also don't forget to send the header Content-Type: application/json

Answer 2

Express 4.0 and above:

$ npm install --save body-parser

And then in your node app:

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

---

Express 3.0 and below:

Try passing this in your cURL call:

--header "Content-Type: application/json"

and making sure your data is in JSON format:

{"user":"someone"}

Also, you can use console.dir in your node.js code to see the data inside the object as in the following example:

var express = require('express');
var app = express.createServer();

app.use(express.bodyParser());

app.post('/', function(req, res){
    console.dir(req.body);
    res.send("test");
}); 

app.listen(3000);

This other question might also help: How to receive JSON in express node.js POST request?

If you don't want to use the bodyParser check out this other question: https://stackoverflow.com/a/9920700/446681

Answer 3

As of Express 4, the following code appears to do the trick. Note that you'll need to install body-parser using npm.

var express = require('express');
var bodyParser = require('body-parser');
var app = express();
app.use(bodyParser.urlencoded({ extended: false }));


app.listen(8888);

app.post('/update', function(req, res) {
    console.log(req.body); // the posted data
});

Answer 4

For 2019, you don't need to install body-parser.

You can use:

var express = require('express');
var app = express();
app.use(express.json())
app.use(express.urlencoded({extended: true}))
app.listen(8888);
app.post('/update', function(req, res) {
    console.log(req.body); // the posted data
});

Answer 5

You should not use body-parser it is deprecated. Try this instead

const express = require('express')
const app = express()

app.use(express.json()) //Notice express.json middleware

The app.use() function is used to mount the specified middleware function(s) at the path which is being specified. It is mostly used to set up middleware for your application.

Now to access the body just do the following

app.post('/', (req, res) => {
  console.log(req.body)
})

Answer 6

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

var port = 9000;

app.post('/post/data', function(req, res) {
    console.log('receiving data...');
    console.log('body is ',req.body);
    res.send(req.body);
});

// start the server
app.listen(port);
console.log('Server started! At http://localhost:' + port);

This will help you. I assume you are sending body in json.

Answer 7

This can be achieved without body-parser dependency as well, listen to request:data and request:end and return the response on end of request, refer below code sample. ref:https://nodejs.org/en/docs/guides/anatomy-of-an-http-transaction/#request-body

var express = require('express');
var app = express.createServer(express.logger());

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

    // push the data to body
    var body = [];
    request.on('data', (chunk) => {
      body.push(chunk);
    }).on('end', () => {
      // on end of data, perform necessary action
      body = Buffer.concat(body).toString();
      response.write(request.body.user);
      response.end();
    });
});

Answer 8

In my case, I was missing to set the header:

"Content-Type: application/json"

Answer 9

Try this:

response.write(JSON.stringify(request.body));

That will take the object which bodyParser has created for you and turn it back into a string and write it to the response. If you want the exact request body (with the same whitespace, etc), you will need data and end listeners attached to the request before and build up the string chunk by chunk as you can see in the json parsing source code from connect.

Answer 10

The accepted answer only works for a body that is compatible with the JSON format. In general, the body can be accessed using

app.use(
  Express.raw({
    inflate: true,
    limit: '50mb',
    type: () => true, // this matches all content types
  })
);

like posted here. The req.body has a Buffer type and can be converted into the desired format.

For example into a string via:

let body = req.body.toString()

Or into JSON via:

let body = req.body.toJSON();

Answer 11

If you're lazy enough to read chunks of post data. you could simply paste below lines to read json.

Below is for TypeScript similar can be done for JS as well.

app.ts

 import bodyParser from "body-parser";
 // support application/json type post data
 this.app.use(bodyParser.json());
 // support application/x-www-form-urlencoded post data
 this.app.use(bodyParser.urlencoded({ extended: false }));

In one of your any controller which receives POST call use as shown below

userController.ts

 public async POSTUser(_req: Request, _res: Response) {
   try {
          const onRecord = <UserModel>_req.body;
           /* Your business logic */
           _res.status(201).send("User Created");
        }
    else{
           _res.status(500).send("Server error");
           }        
   };

_req.body should be parsing you json data into your TS Model.

Answer 12

I'm absolutely new to JS and ES, but what seems to work for me is just this:

JSON.stringify(req.body)

Let me know if there's anything wrong with it!

Answer 13

Install Body Parser by below command

$ npm install --save body-parser

Configure Body Parser

const bodyParser = require('body-parser');
app.use(bodyParser);
app.use(bodyParser.json()); //Make sure u have added this line
app.use(bodyParser.urlencoded({ extended: false }));

Answer 14

for people who dont want to use express JSON middleware because they need to be more flexible: you can use the raw nodejs api for it.

How to call it:

const body = await getBody(request);

the function:

function getBody(request) {
  return new Promise((resolve, reject) => {
    const bodyParts = [];

    request.on('error', (error) => {
      console.log(error);
      reject(error);
    })
    
    request.on('data', (chunk) => {
      bodyParts.push(chunk);
    })
    
    request.on('end', () => {
      const body = Buffer.concat(bodyParts).toString();
      resolve(body);
    });
  });
}

source, but converted to promise to be awaitable: https://nodejs.org/en/docs/guides/anatomy-of-an-http-transaction

for typescript: the type of chunk is Buffer and of bodyParts it is Buffer[]

Answer 15

Note that if you put your request with a form the Content-type is application/x-www-form-urlencoded You could use a middleware, as of Express 4.16, like app.use(express.json()) but in this way doesn't work because it expects application\json: in that case to change the content-type of your POST request you have to use Ajax. Another way is to use another middleware like that:

app.use(express.urlencoded({ extended: false }));

where the content-type is the same of the form by default.

Answer 16

What you claim to have "tried doing" is exactly what you wrote in the code that works "as expected" when you invoke it with curl.

The error you're getting doesn't appear to be related to any of the code you've shown us.

If you want to get the raw request, set handlers on request for the data and end events (and, of course, remove any invocations of express.bodyParser()). Note that the data events will occur in chunks, and that unless you set an encoding for the data event those chunks will be buffers, not strings.

Answer 17

You use the following code to log post data:

router.post("/users",function(req,res){
    res.send(JSON.stringify(req.body, null, 4));
});