CODEWITHSUNDEEP
jsonnode.jsexpress
Avery246813579
Avery246813579

Reputation: 309

How do you reject an invalid JSON body using Express or Body-Parser

I'm creating an application that only accepts a body type of json and uses body-parsers and express. The problem that keeps showing up is if I send an invalid json body, then my program will throw a stupid error back to the user, and in the console. How would I prevent this console error and reject a request with an improper JSON body.

Thanks in advance, Avery.

PS. Here is some example code to show what I'm doing: 

var bodyParser = require('body-parser');
var express = require('express');
var app = express();

app.use(bodyParser.json());

app.post('/test', function(req, res){
   res.status(200).send("Hi");
});

app.listen(8081, function(){
   console.log("Server is running");
});

Upvotes: 5

Views: 3976

Answers (2)

Naor Tedgi
Naor Tedgi

Reputation: 5707

body parser throw all kind of errors for example

'encoding.unsupported', 'entity.parse.failed', 'entity.verify.failed', 'request.aborted', 'request.size.invalid', 'stream.encoding.set', 'parameters.too.many', 'charset.unsupported', 'encoding.unsupported', 'entity.too.large'

if you want a more robust solution use this middleware

https://www.npmjs.com/package/express-body-parser-error-handler

$ npm i express-body-parser-error-handler

for example:

const bodyParserErrorHandler = require('express-body-parser-error-handler')
const { urlencoded, json } = require('body-parser')
const express = require('express')
const app = express();
router.route('/').get(function (req, res) {
    return res.json({message:"🚀"});
});

// body parser initilization
app.use('/', json({limit: '250'}));

// body parser error handler
app.use(bodyParserErrorHandler());
app.use(router);
...

Upvotes: 0

Paul
Paul

Reputation: 36319

You need to attach some error handling middleware to your app. How you handle that error is up to you, but as an example of how you'd do it: 

var bodyParser = require('body-parser');
var express = require('express');
var app = express();

app.use(bodyParser.json());

// this is a trivial implementation
app.use((err, req, res, next) => {
  // you can error out to stderr still, or not; your choice
  console.error(err); 

  // body-parser will set this to 400 if the json is in error
  if(err.status === 400)
    return res.status(err.status).send('Dude, you messed up the JSON');

  return next(err); // if it's not a 400, let the default error handling do it. 
});

app.post('/test', function(req, res){
   res.status(200).send("Hi");
});

app.listen(8081, function(){
   console.log("Server is running");
});

Upvotes: 9

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