javascript - express.js req.body undefined in middleware

Question

I'm currently facing a problem in my node application.

while trying to use middleware in a post request the req.body becomes undefined.

for example;

router.post('/newpost', ensureAuthenticated, createPost, upload.single('file'), async (req, res) =>{
    console.log(req.body);
}

async function createPost(req, res, next){
    console.log(req.body);
    next();
}

when the createPost function runs it logs req.body as undefined. but when req.body gets logged inside the router.post it is defined.

is it something i'm missing? or is this just not possible to do.

also i've ensured that i've included bodyparser and initialized it before my routes.

question from:https://stackoverflow.com/questions/65907925/express-js-req-body-undefined-in-middleware

Answer 1

well, I've just tested and all works fine, with my suggestion in the comment

here's the content of my test:

my index.js

const express = require('express')

const router = express.Router()
const app = express()
const PORT = process.env.PORT || 3002

app.use(express.json())

const createPost = (req, res, next) => {
    console.log('createPost', req.body)
    next()
}

router.post('/newpost', createPost, (req, res) => {
    console.log('/nextpost', req.body)
    res.json({ message: 'ok' })
})

app.use('/', router)

app.listen(PORT, () => {
    console.log(
        `server ready at http://localhost:${PORT}`
    )
})

and a simple REST Client file

@HOST = http://localhost:3002

POST {{HOST}}/newpost
Content-Type: application/json

{
    "fname": "Bruno",
    "lname": "Alexandre",
    "nick": "balexandre"
}

and the result is

? node .index.js
server ready at http://localhost:3002
createPost { fname: 'Bruno', lname: 'Alexandre', nick: 'balexandre' }
/nextpost { fname: 'Bruno', lname: 'Alexandre', nick: 'balexandre' }

and the response of the call

HTTP/1.1 200 OK
X-Powered-By: Express
Content-Type: application/json; charset=utf-8
Content-Length: 16
ETag: W/"10-/VnJyQBB0+b7i4NY83P42KKVWsM"
Date: Tue, 26 Jan 2021 19:59:21 GMT
Connection: close

{
  "message": "ok"
}

screenshot (click for full image)

---

Warning

make sure you're passing Content-Type: application/json in your POST request, remember that you told Express that you wanted the body parsed as .json() so make sure it knows you're passing json as the request body

a bit more information... the req.body is only undefined if I do not use the parser, like:

---

Added

a GitHub repository with working solution > https://github.com/balexandre/so65907925