NextJS and React: Cannot read property 'email' of undefined

Question

I try to send data from my client to my server. For that, i use React with NextJS, because you have the server and client-side in one app.

I use the following handleSubmitFunction:

handleSubmit() {
  const email = this.state.email;
  fetch('/', {
    method: 'POST',
    body: email,
  });
}

and this is my server.js file in the located in / at my project

const express = require('express')
const next = require('next')
const bodyParser = require('body-parser')

const dev = process.env.NODE_ENV !== 'production'
const app = next({ dev })
const handle = app.getRequestHandler()

app.prepare()
.then(() => {
  const server = express()

  //parse application
  server.use(bodyParser.urlencoded({ extended: false}))

  //parse application/json
  server.use(bodyParser.json())

  server.post('/', (req, res) => {
    console.log(req.body.email);
    res.end("success!");
  })

  server.get('*', (req, res) => {
    return handle(req, res)
  })

  server.listen(3000, (err) => {
    if (err) throw err
    console.log('> Ready on http://localhost:3000')
  })
})
.catch((ex) => {
  console.error(ex.stack)
  process.exit(1)
})

When the handleSubmit Function is running, i get the following Output from the Server Console:

Cannot read property 'email' of undefined

Where exactly is my mistake? I have little experience in node JS environments. I would be very grateful if you could show me concrete solutions. Thank you for your replies.

Klaus Pedersen · Accepted Answer · 2018-09-28 14:52:43Z

2

It seems you have to parse header and JSON.stringify the email.

fetch('/', {
      method: 'POST',
      headers: {
        'Accept': 'application/json',
        'Content-Type': 'application/json'
      },
      body: JSON.stringify({email:email}),
    }).then((res)=> console.log('Worked'))

answered Sep 28, 2018 at 14:52

Klaus Pedersen

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1 Comment

Niklas Over a year ago

i added another question: stackoverflow.com/questions/52559046/…? Could you look at the question?

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