DeprecationWarnings in nodejs application

Question

my user.js

const express=require('express')
const router=express.Router()
const gravatar=require('gravatar')
const bcrypt=require('bcryptjs')
const {check,validationResult} =require('express-validator/check')

const User=require('../../models/User')

//@route  POST api/users
//@desc   Register user
//@access public
router.post('/',[
check('name','Name is required').not().isEmpty(),
check('email','please include a valid email').isEmail(),
check('password','please enter password with more than 6 characters').isLength({min:6})
],async(req,res)=>{
const errors=validationResult(req);
if(!errors.isEmpty()){
    return res.status(400).json({errors:errors.array()})
}

const {name,email,password}=req.body;

try{
 //see if the user exists
let user = await User.findOne({ email: email })

//if record exists in DB
if (user) {
    return res.status(400).json({ errors: [{ msg: "user already exists" }] });
}

 //get users gravatar
 const avatar=gravatar.url(email,{
     s:'200', //size
     r:'pg',  //rating of image
     d:'mm'   //gives a default image
 })
user=new User({
    name,
    email,
    avatar,
    password
})
 //encrpyt password 
 const salt=await bcrypt.genSalt(10) // 10-no of rounds.more the better

 user.password=await bcrypt.hash(password,salt); //coverts to hash pass

 await user.save();

 //return jsonwebtoken

 res.send('User registered')
}catch(e){
    console.log(e.message)
    res.status(500).send('server error')
}

res.send('User route')
})

module.exports=router;

the app is working fine but in the terminal i get

(node:1022) UnhandledPromiseRejectionWarning: Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client at ServerResponse.setHeader (_http_outgoing.js:464:11) at ServerResponse.header (/Users/udayshetty/Desktop/MERN app/node_modules/express/lib/response.js:771:10) at ServerResponse.send (/Users/udayshetty/Desktop/MERN app/node_modules/express/lib/response.js:170:12) at /Users/udayshetty/Desktop/MERN app/routes/api/users.js:60:9 at processTicksAndRejections (internal/process/task_queues.js:85:5) (node:1022) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1) (node:1022) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

You have `res.send('User route')` at the very bottom which is trying to send a second response. Just remove that and the error should disappear. — , Nov 12 '19 at 14:40
line 60 in users.js is res.send('User route'), remove that unnecesary line — SuleymanSah, Nov 12 '19 at 14:41
Possible duplicate of [Error: Can't set headers after they are sent to the client](https://stackoverflow.com/questions/7042340/error-cant-set-headers-after-they-are-sent-to-the-client) — , Nov 12 '19 at 15:03

score 0 · Accepted Answer · answered Nov 12 '19 at 14:41

This error occurs when your app is responding to the client over HTTP - and you try to send the response / response headers twice. Once the response is sent, the connection will be closed. You can only send them once for a given http request. You can keep a connection open and send more data , but you cannot send the response headers again.

Please try to remove res.send('User route').

You are sending a response twice.

DeprecationWarnings in nodejs application

1 Answers1