Parsing JSON in Express without BodyParser

Question

I'm trying to write a simple express server that takes incoming JSON (POST), parses the JSON and assigns to the request body. The catch is I cannot use bodyparser. Below is my server with a simple middleware function being passed to app.use

Problem: whenever I send dummy POST requests to my server with superagent (npm package that lets you send JSON via terminal) my server times out. I wrote an HTTP server in a similar fashion using req.on('data')...so I'm stumped. Any advice?

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

function jsonParser(req, res, next) {
  res.writeHead(200, {'Content-Type:':'application/json'});
  req.on('data', (data, err) => {
    if (err) res.status(404).send({error: "invalid json"});
    req.body = JSON.parse(data);
  });
  next();
};

app.use(jsonParser);
app.post('/', (req, res) => {
  console.log('post request logging message...');
});

app.listen(3000, () => console.log('Server running on port 3000'));

Solution 1

I think the problem like to get rawBody in express.

Just like this:

app.use(function(req, res, next){
   var data = "";
   req.on('data', function(chunk){ data += chunk})
   req.on('end', function(){
       req.rawBody = data;
       req.jsonBody = JSON.parse(data);
       next();
   })
})

And you need catch the error when parse the string to json and need to judge the Content-type of the Req.

Good luck.

Solution 2

another way that worked with me by collecting all chunks into an array and parsing the concatenated chunks.

app.use("/", (req, res, next)=>{

    const body = [];
    req.on("data", (chunk) => {
        console.log(chunk);
        body.push(chunk);
    });
    req.on("end", () => {
        const parsedBody = Buffer.concat(body).toString();
        const message = parsedBody.split('=')[1];
        console.log(parsedBody);
        console.log(message);
    });
    console.log(body);
});

Comments

[Michael]

For some weird reason, JSON.parse is throwing an exception because data is empty in end, but if I catch it, req.rawBody has the JSON text later.