Express.json() works on local but not on AWS Lambda

Question

I've been struggling to parse the request body from POST. I tested the code locally via curl and returns the json body. On Lambda, I tried both curl and Postman but it just returned the buffer data.

Basically, I can't manipulate the data.

index.js

require('dotenv').config();
const express = require('express');
const bodyParser = require('body-parser');
const serverless = require('serverless-http');

const app = express();
app.use(express.json());
// app.use(bodyParser.json());

// Routes
app.use('/db', require('./routes/db'));

module.exports.handler = serverless(app);

routes > db.js

const express = require('express');
const { Pool } = require('pg');
const router = express.Router();

// Test
router.post('/test', (req, res) => {
  console.log('Raw req.body:', req.body);
  res.json({ received: req.body });
});


module.exports = router;

Sample request:

{
  "movetype": 1
}

This is the response using Postman:

{
    "received": {
        "type": "Buffer",
        "data": [
            123,
            13,
            10,
            32,
            32,
            34,
            109,
            111,
            118,
            101,
            116,
            121,
            112,
            101,
            34,
            58,
            32,
            49,
            13,
            10,
            125,
            13,
            10
        ]
    }
}

Answer 1

The problem is that you're most likely using latest body-parser with Express 5, which causes conflict with serverless-http you're also using.

see:

body-parser middleware not triggering in Express 5/body-parser 2.x #274

Parser does not work in serverless environment #608

Suggested workaround is to convert body to JSON when it's a buffer on your own.

see:

Buffer in request.body #297

export const handler = serverless(app, { request: (req) => { if (Buffer.isBuffer(req.body)) { try { req.body = JSON.parse(req.body.toString()); } catch (e) { console.error('Failed to parse body as JSON', e); } } }, })