javascript - can't do POST to api, error 400 using fetch - Stack Overflow

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fetch('/auth/signup', {
      method: 'POST',
      body: this.state.user,
      headers: {
        'Content-Type': 'application/json'
      },
    })
    .then(function(response) {
      return response.json();
    })
    .then(data => {
      console.log(data);
    })

this.state.user is basically an object like {user: {name:"someone"} and my server side code simply do this

router.post('/signup', (req, res, next) => {
  console.log(req.body) // empty object
}

I think something is wrong with fetch, didn't see any data been pass in the network tab.

fetch('/auth/signup', {
      method: 'POST',
      body: this.state.user,
      headers: {
        'Content-Type': 'application/json'
      },
    })
    .then(function(response) {
      return response.json();
    })
    .then(data => {
      console.log(data);
    })

this.state.user is basically an object like {user: {name:"someone"} and my server side code simply do this

router.post('/signup', (req, res, next) => {
  console.log(req.body) // empty object
}

I think something is wrong with fetch, didn't see any data been pass in the network tab.

• javascript
• ajax
• reactjs
• fetch

Share Improve this question Follow asked Apr 22, 2017 at 3:25 Jenny MokJenny Mok 2,80499 gold badges3333 silver badges6262 bronze badges 4

• Do you see a certain message in your [console] window? – Marylyn Lajato Commented Apr 22, 2017 at 3:31
• @eeya 400 error, bad request – Jenny Mok Commented Apr 22, 2017 at 3:32
• On your [fetch] method, what happens when you replace the url to 'signup' instead of 'auth/signup'? – Marylyn Lajato Commented Apr 22, 2017 at 3:37
• @eeya now I manage to pass data but server return req.body as {} hmmm... – Jenny Mok Commented Apr 22, 2017 at 3:40

Add a ment  | 

1 Answer 1

Sorted by: Reset to default 8

Pass this.state.user to JSON.stringify() before setting at body or use FormData to POST key, value pairs. body does not expect javascript object.

body: JSON.stringify(this.state.user)

let fd = new FormData();
let {user} = this.state.user;
for (let prop in user) {
  fd.append(prop, JSON.stringify(user[prop]));
}

body: fd

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