Can't get POST data using NodeJS/ExpressJS and Postman

问题

This is the code of my server :

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

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

app.listen(3000, function () {
    console.log('Example app listening on port 3000!');
});

From Postman, I launch a POST request to http://localhost:3000/ and in Body/form-data I have a key "foo" and value "bar".

However I keep getting an empty object in the response. The req.body property is always empty.

Did I miss something?

回答1:

Add the encoding of the request. Here is an example

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

Then select x-www-form-urlencoded in Postman or set Content-Type to application/json and select raw

Edit for use of raw

Raw

{
  "foo": "bar"
}

Headers

Content-Type: application/json

EDIT #2 Answering questions from chat:

why it can't work with form-data?

You sure can, just look at this answer How to handle FormData from express 4

What is the difference between using x-www-form-urlencoded and raw

differences in application/json and application/x-www-form-urlencoded

回答2:

let express = require('express');
let app = express();

// For POST-Support
let bodyParser = require('body-parser');
let multer = require('multer');
let upload = multer();

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

app.post('/api/sayHello', upload.array(), (request, response) => {
    let a = request.body.a;
    let b = request.body.b;


    let c = parseInt(a) + parseInt(b);
    response.send('Result : '+c);
    console.log('Result : '+c);
});

app.listen(3000);

Sample JSON and result of the JSON:

Set Content-typeL application/JSON:

回答3:

I encountered this problem while using routers. Only GET was working, POST, PATCH and delete was reflecting "undefined" for req.body. After using the body-parser in the router files, I was able to get all the HTTP methods working...

Here is how I did it:

...
const bodyParser = require('body-parser')
...
router.use(bodyParser.json());
router.use(bodyParser.urlencoded({ extended: true }));
...
...
// for post
router.post('/users', async (req, res) => {
    const user = await new User(req.body) // here is where I was getting req.body as undefined before using body-parser
    user.save().then(() => {
        res.status(201).send(user)
    }).catch((error) => {
        res.status(400).send(error)
    })
})

For PATCH and DELETE as well, this trick suggested by user568109 worked.

回答4:

On more point I want to add is if you created your project through Express.js generator in your app.js it also generates bellow code

app.use(express.json());

if you put your body-parser above this code the req.body will return null or undefined you should put it bellow the above code see bellow for correct placement

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

来源：https://stackoverflow.com/questions/41955103/cant-get-post-data-using-nodejs-expressjs-and-postman

标签

node.js

express

postman

body-parser