Unexpected token - in JSON at position 0 (express js server)-CodePudding

I am trying to send form data to my express js backend.

for my backend server i have this in my server.js file

import express from 'express';
import { routes } from './routes/routes.js'
import connectdb from './model/db.js'
import { getAll } from './model/db.js';

const app = express();
const {projectRoute, fileRoute} = routes

// json parser
app.use(express.json());
app.use(express.urlencoded({ extended: true }));
app.use(function(req, res, next) {
  res.header("Access-Control-Allow-Origin", "*")
  res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept")
  next()
})

const port = process.env.PORT || 5000;

// database connection 
connectdb()


// router for all the project endpoint
app.use("/project", projectRoute);
// router for all the files endpoint
app.use("/files", fileRoute);

app.listen(port, () => {
  console.log(`listening at port ${port}`);
});

and in the controller file for the "fileRoute", i'm simply trying to see what gets sent in the req.body object. This is the form data i send

But each time i send the request using VS code Thunderclient, i get this error

Unexpected token - in JSON at position 0 (express js server)

and when i set the content-type header to application/x-www-form-urlencoded i get req.body sent back as this

{   "----------------------------482425439322439335041238\r\nContent-Disposition: form-data; name": "\"project\"\r\n\r\nHTML Project\r\n----------------------------482425439322439335041238\r\nContent-Disposition: form-data; name=\"date\"\r\n\r\n2022-08-10\r\n----------------------------482425439322439335041238--\r\n" }

i don't understand why this is hapening, can anyone help??

i expected a json body as my result, and when i used a json validator to check this response

{   "----------------------------482425439322439335041238\r\nContent-Disposition: form-data; name": "\"project\"\r\n\r\nHTML Project\r\n----------------------------482425439322439335041238\r\nContent-Disposition: form-data; name=\"date\"\r\n\r\n2022-08-10\r\n----------------------------482425439322439335041238--\r\n" }

it returned VALID (RFC 8259)

CodePudding user response：

This is happening because:

you're uploading the data as multipart/form-data, as shown in your "Body" screen shot; and
you're overriding the Content-Type header to application/json.

The header makes Express think that the body content is JSON-formatted, which it isn't (it's MIME multipart formatted).

To fix this, don't use the "Body > Form" tab in Postman (remove all the fields there) but the "Body > Json" tab.

CodePudding user response：

Ok .. so i still haven't found a solution to this problem on the internet. Although it did start working normally a few days after posting this question, unfortunately the issue came back and has persisted since.

So instead of crying about it, i decided to create a solution of mine, so i wrote my own body parser middleware based on the result i was getting. Here's the code