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Fetch POST method gives empty body on Express server

I make a POST request from my browser client:
const post = async (url, body) => {
try {
const response = await fetch(url, {
method: `POST`,
headers: {
'Content-Type': 'application/x-www-form-urlencoded',
},
body
});
return response.json();
} catch (error) {
console.log(error.stack);
}
}
const data = await post(`http://localhost:4050/analyze`, { text });
And I handle it on Express server with this setup:
app.use(express.urlencoded({ extended: true }));
This is my route:
router.post(`/`, errorHandler(async (req, res, next) => {
const { text } = req.body;
console.log(req.body)
const value = await analyze(text);
res.json({ rephrased });
}));
The console.log shows me this:
{ 'object Object': '' }
Why fetch method gives me Object instead of text property?
UPDATE:
When I do Stringify:
method: `POST`,
headers: {
'Content-Type': 'application/x-www-form-urlencoded',
},
body: JSON.stringify(body)
The body became like this and console.log shows:
{ '{"text":"asdfasdf"}': '' }

You are passing fetch a plain object for the body and it doesn't know what to do with it, so it calls .toString() and gives you nothing useful.
Pass it a URLSearchParams object instead. (Here I assume text is a string)
const body = new URLSearchParams();
body.append("text", text);
This will convert to a application/x-www-form-urlencoded string.
(You can also omit the headers as fetch can infer the correct Content-Type from the URLSearchParams object.)
Re edit: JSON.stringify will encode the data as JSON. JSON is not application/x-www-form-urlencoded.

axios vs fetch throwing error on file upload

I am using fetch instead of axios in my react project
my this method working fine with the axios to upload an image on the server
Upload image function
<Upload customRequest={dummyRequest} className="upload-btn-container" onChange={onChange}>
<Button className="btn custom-upload-btn">Upload Image</Button>
</Upload>
const uploadPicture = async (data) =>{
const value = await getUploadPicture(data)
if(value.value.data.status){
await addImage(value.value.data.data)
}
}
const onChange = async (info) => {
for (let i = 0; i < info.fileList.length; i++) {
const data = new FormData();
data.append('file', info.fileList[i]);
data.append('filename', info.fileList[i].name);
setImgName(info.fileList[i].name)
let value = await uploadPicture(data);
}
};
return axios({
method: 'post',
url: `${NewHostName}/upload`,
headers: {
'Content-Type': 'application/json',
'Authorization': localStorage.getItem('authToken')
},
data:data
})
.then(response => {
return response
}).catch(err => {
console.log("err", err)
})
whereas when I do same with the fetch it throws me error on the backend "Cannot read property of split of undefined"
return fetch(`${NewHostName}/upload`, {
method: "post",
headers: {
"Content-Type": "application/json",
Authorization: localStorage.getItem('authToken'),
},
body: JSON.stringify(data),
// body :data
})
.then((res) => {
return res.json();
})
.then((payload) => {
return payload;
})
.catch((err) => {
throw err;
})
Not sure what is the reason behind this
this is my backend upload api
const handler = async (request, reply) => {
try {
const filename = request.payload.filename
const fileExtension = filename.split('.').pop()
AWS.config.update({
accessKeyId: Config.get('/aws').accessKeyId,
secretAccessKey: Config.get('/aws').secretAccessKey,
region: Config.get('/aws').region
})
const s3 = new AWS.S3({
params: {
Bucket: Config.get('/aws').bucket
}
})
const Key = `/${shortid.generate()}.${fileExtension}`
const obj = {
Body: request.payload.file,
Key,
ACL: 'public-read'
}
s3.upload(obj, async (err, data) => {
if (err) {
return reply({ status: false, 'message': err.message, data: '' }).code(Constants.HTTP402)
} else if (data) {
return reply({ status: true, 'message': 'ok', data: data.Location }).code(Constants.HTTP200)
}
})
} catch (error) {
return reply({
status: false,
message: error.message,
data: ''
})
}
}

data is a FormData object.
In your original code you are lying when you say 'Content-Type': 'application/json'. Possibly Axios recognises that you've passed it a FormData object and ignores your attempt to override the Content-Type.
Your fetch code, on the other hand, says body: JSON.stringify(data) which tries to stringify the FormData object and ends up with "{}" which has none of your data in it.
Don't claim you are sending JSON
Don't pass your FormData object through JSON.stringify

For image upload you not use JSON.stringify(data).You can try with formData and append an image file with form data.
var formdata = new FormData();
formdata.append("image", data);

Did you check that
const filename = request.payload.filename
exists?
Is the key really payload? The following does not make any changes to your code:
.then((payload) => {
return payload;
})

How to post file data to Gitlab project using JavaScript fetch [duplicate]

I'm trying to POST a JSON object using fetch.
From what I can understand, I need to attach a stringified object to the body of the request, e.g.:
fetch("/echo/json/",
{
headers: {
'Accept': 'application/json',
'Content-Type': 'application/json'
},
method: "POST",
body: JSON.stringify({a: 1, b: 2})
})
.then(function(res){ console.log(res) })
.catch(function(res){ console.log(res) })
When using jsfiddle's JSON echo I'd expect to see the object I've sent ({a: 1, b: 2}) back, but this does not happen - chrome devtools doesn't even show the JSON as part of the request, which means that it's not being sent.

With ES2017 async/await support, this is how to POST a JSON payload:
(async () => {
const rawResponse = await fetch('https://httpbin.org/post', {
method: 'POST',
headers: {
'Accept': 'application/json',
'Content-Type': 'application/json'
},
body: JSON.stringify({a: 1, b: 'Textual content'})
});
const content = await rawResponse.json();
console.log(content);
})();
Can't use ES2017? See #vp_art's answer using promises
The question however is asking for an issue caused by a long since fixed chrome bug.
Original answer follows.
chrome devtools doesn't even show the JSON as part of the request
This is the real issue here, and it's a bug with chrome devtools, fixed in Chrome 46.
That code works fine - it is POSTing the JSON correctly, it just cannot be seen.
I'd expect to see the object I've sent back
that's not working because that is not the correct format for JSfiddle's echo.
The correct code is:
var payload = {
a: 1,
b: 2
};
var data = new FormData();
data.append( "json", JSON.stringify( payload ) );
fetch("/echo/json/",
{
method: "POST",
body: data
})
.then(function(res){ return res.json(); })
.then(function(data){ alert( JSON.stringify( data ) ) })
For endpoints accepting JSON payloads, the original code is correct

I think your issue is jsfiddle can process form-urlencoded request only. But correct way to make json request is pass correct json as a body:
fetch('https://httpbin.org/post', {
method: 'POST',
headers: {
'Accept': 'application/json, text/plain, */*',
'Content-Type': 'application/json'
},
body: JSON.stringify({a: 7, str: 'Some string: &=&'})
}).then(res => res.json())
.then(res => console.log(res));

From search engines, I ended up on this topic for non-json posting data with fetch, so thought I would add this.
For non-json you don't have to use form data. You can simply set the Content-Type header to application/x-www-form-urlencoded and use a string:
fetch('url here', {
method: 'POST',
headers: {'Content-Type':'application/x-www-form-urlencoded'}, // this line is important, if this content-type is not set it wont work
body: 'foo=bar&blah=1'
});
An alternative way to build that body string, rather then typing it out as I did above, is to use libraries. For instance the stringify function from query-string or qs packages. So using this it would look like:
import queryString from 'query-string'; // import the queryString class
fetch('url here', {
method: 'POST',
headers: {'Content-Type':'application/x-www-form-urlencoded'}, // this line is important, if this content-type is not set it wont work
body: queryString.stringify({for:'bar', blah:1}) //use the stringify object of the queryString class
});

After spending some times, reverse engineering jsFiddle, trying to generate payload - there is an effect.
Please take eye (care) on line return response.json(); where response is not a response - it is promise.
var json = {
json: JSON.stringify({
a: 1,
b: 2
}),
delay: 3
};
fetch('/echo/json/', {
method: 'post',
headers: {
'Accept': 'application/json, text/plain, */*',
'Content-Type': 'application/json'
},
body: 'json=' + encodeURIComponent(JSON.stringify(json.json)) + '&delay=' + json.delay
})
.then(function (response) {
return response.json();
})
.then(function (result) {
alert(result);
})
.catch (function (error) {
console.log('Request failed', error);
});
jsFiddle: http://jsfiddle.net/egxt6cpz/46/ && Firefox > 39 && Chrome > 42

2021 answer: just in case you land here looking for how to make GET and POST Fetch api requests using async/await or promises as compared to axios.
I'm using jsonplaceholder fake API to demonstrate:
Fetch api GET request using async/await:
const asyncGetCall = async () => {
try {
const response = await fetch('https://jsonplaceholder.typicode.com/posts');
const data = await response.json();
// enter you logic when the fetch is successful
console.log(data);
} catch(error) {
// enter your logic for when there is an error (ex. error toast)
console.log(error)
}
}
asyncGetCall()
Fetch api POST request using async/await:
const asyncPostCall = async () => {
try {
const response = await fetch('https://jsonplaceholder.typicode.com/posts', {
method: 'POST',
headers: {
'Content-Type': 'application/json'
},
body: JSON.stringify({
// your expected POST request payload goes here
title: "My post title",
body: "My post content."
})
});
const data = await response.json();
// enter you logic when the fetch is successful
console.log(data);
} catch(error) {
// enter your logic for when there is an error (ex. error toast)
console.log(error)
}
}
asyncPostCall()
GET request using Promises:
fetch('https://jsonplaceholder.typicode.com/posts')
.then(res => res.json())
.then(data => {
// enter you logic when the fetch is successful
console.log(data)
})
.catch(error => {
// enter your logic for when there is an error (ex. error toast)
console.log(error)
})
POST request using Promises:
fetch('https://jsonplaceholder.typicode.com/posts', {
method: 'POST',
headers: {
'Content-Type': 'application/json',
},
body: JSON.stringify({
// your expected POST request payload goes here
title: "My post title",
body: "My post content."
})
})
.then(res => res.json())
.then(data => {
// enter you logic when the fetch is successful
console.log(data)
})
.catch(error => {
// enter your logic for when there is an error (ex. error toast)
console.log(error)
})
GET request using Axios:
const axiosGetCall = async () => {
try {
const { data } = await axios.get('https://jsonplaceholder.typicode.com/posts')
// enter you logic when the fetch is successful
console.log(`data: `, data)
} catch (error) {
// enter your logic for when there is an error (ex. error toast)
console.log(`error: `, error)
}
}
axiosGetCall()
POST request using Axios:
const axiosPostCall = async () => {
try {
const { data } = await axios.post('https://jsonplaceholder.typicode.com/posts', {
// your expected POST request payload goes here
title: "My post title",
body: "My post content."
})
// enter you logic when the fetch is successful
console.log(`data: `, data)
} catch (error) {
// enter your logic for when there is an error (ex. error toast)
console.log(`error: `, error)
}
}
axiosPostCall()

I have created a thin wrapper around fetch() with many improvements if you are using a purely json REST API:
// Small library to improve on fetch() usage
const api = function(method, url, data, headers = {}){
return fetch(url, {
method: method.toUpperCase(),
body: JSON.stringify(data), // send it as stringified json
credentials: api.credentials, // to keep the session on the request
headers: Object.assign({}, api.headers, headers) // extend the headers
}).then(res => res.ok ? res.json() : Promise.reject(res));
};
// Defaults that can be globally overwritten
api.credentials = 'include';
api.headers = {
'csrf-token': window.csrf || '', // only if globally set, otherwise ignored
'Accept': 'application/json', // receive json
'Content-Type': 'application/json' // send json
};
// Convenient methods
['get', 'post', 'put', 'delete'].forEach(method => {
api[method] = api.bind(null, method);
});
To use it you have the variable api and 4 methods:
api.get('/todo').then(all => { /* ... */ });
And within an async function:
const all = await api.get('/todo');
// ...
Example with jQuery:
$('.like').on('click', async e => {
const id = 123; // Get it however it is better suited
await api.put(`/like/${id}`, { like: true });
// Whatever:
$(e.target).addClass('active dislike').removeClass('like');
});

Had the same issue - no body was sent from a client to a server.
Adding Content-Type header solved it for me:
var headers = new Headers();
headers.append('Accept', 'application/json'); // This one is enough for GET requests
headers.append('Content-Type', 'application/json'); // This one sends body
return fetch('/some/endpoint', {
method: 'POST',
mode: 'same-origin',
credentials: 'include',
redirect: 'follow',
headers: headers,
body: JSON.stringify({
name: 'John',
surname: 'Doe'
}),
}).then(resp => {
...
}).catch(err => {
...
})

This is related to Content-Type. As you might have noticed from other discussions and answers to this question some people were able to solve it by setting Content-Type: 'application/json'. Unfortunately in my case it didn't work, my POST request was still empty on the server side.
However, if you try with jQuery's $.post() and it's working, the reason is probably because of jQuery using Content-Type: 'x-www-form-urlencoded' instead of application/json.
data = Object.keys(data).map(key => encodeURIComponent(key) + '=' + encodeURIComponent(data[key])).join('&')
fetch('/api/', {
method: 'post',
credentials: "include",
body: data,
headers: {'Content-Type': 'application/x-www-form-urlencoded'}
})

The top answer doesn't work for PHP7, because it has wrong encoding, but I could figure the right encoding out with the other answers. This code also sends authentication cookies, which you probably want when dealing with e.g. PHP forums:
julia = function(juliacode) {
fetch('julia.php', {
method: "POST",
credentials: "include", // send cookies
headers: {
'Accept': 'application/json, text/plain, */*',
//'Content-Type': 'application/json'
"Content-Type": "application/x-www-form-urlencoded; charset=UTF-8" // otherwise $_POST is empty
},
body: "juliacode=" + encodeURIComponent(juliacode)
})
.then(function(response) {
return response.json(); // .text();
})
.then(function(myJson) {
console.log(myJson);
});
}

It might be useful to somebody:
I was having the issue that formdata was not being sent for my request
In my case it was a combination of following headers that were also causing the issue and the wrong Content-Type.
So I was sending these two headers with the request and it wasn't sending the formdata when I removed the headers that worked.
"X-Prototype-Version" : "1.6.1",
"X-Requested-With" : "XMLHttpRequest"
Also as other answers suggest that the Content-Type header needs to be correct.
For my request the correct Content-Type header was:
"Content-Type": "application/x-www-form-urlencoded; charset=UTF-8"
So bottom line if your formdata is not being attached to the Request then it could potentially be your headers. Try bringing your headers to a minimum and then try adding them one by one to see if your problem is resolved.

If your JSON payload contains arrays and nested objects, I would use URLSearchParams and jQuery's param() method.
fetch('/somewhere', {
method: 'POST',
body: new URLSearchParams($.param(payload))
})
To your server, this will look like a standard HTML <form> being POSTed.

You could do it even better with await/async.
The parameters of http request:
const _url = 'https://jsonplaceholder.typicode.com/posts';
let _body = JSON.stringify({
title: 'foo',
body: 'bar',
userId: 1,
});
const _headers = {
'Content-type': 'application/json; charset=UTF-8',
};
const _options = { method: 'POST', headers: _headers, body: _body };
With clean async/await syntax:
const response = await fetch(_url, _options);
if (response.status >= 200 && response.status <= 204) {
let data = await response.json();
console.log(data);
} else {
console.log(`something wrong, the server code: ${response.status}`);
}
With old fashion fetch().then().then():
fetch(_url, _options)
.then((res) => res.json())
.then((json) => console.log(json));

**//POST a request**
const createTodo = async (todo) => {
let options = {
method: "POST",
headers: {
"Content-Type":"application/json",
},
body: JSON.stringify(todo)
}
let p = await fetch("https://jsonplaceholder.typicode.com/posts", options);
let response = await p.json();
return response;
}
**//GET request**
const getTodo = async (id) => {
let response = await fetch('https://jsonplaceholder.typicode.com/posts/' + id);
let r = await response.json();
return r;
}
const mainFunc = async () => {
let todo = {
title: "milan7",
body: "dai7",
userID: 101
}
let todor = await createTodo(todo);
console.log(todor);
console.log(await getTodo(5));
}
mainFunc()

I think that, we don't need parse the JSON object into a string, if the remote server accepts json into they request, just run:
const request = await fetch ('/echo/json', {
headers: {
'Content-type': 'application/json'
},
method: 'POST',
body: { a: 1, b: 2 }
});
Such as the curl request
curl -v -X POST -H 'Content-Type: application/json' -d '#data.json' '/echo/json'
In case to the remote serve not accept a json file as the body, just send a dataForm:
const data = new FormData ();
data.append ('a', 1);
data.append ('b', 2);
const request = await fetch ('/echo/form', {
headers: {
'Content-type': 'application/x-www-form-urlencoded'
},
method: 'POST',
body: data
});
Such as the curl request
curl -v -X POST -H 'Content-type: application/x-www-form-urlencoded' -d '#data.txt' '/echo/form'

You only need to check if response is ok coz the call not returning anything.
var json = {
json: JSON.stringify({
a: 1,
b: 2
}),
delay: 3
};
fetch('/echo/json/', {
method: 'post',
headers: {
'Accept': 'application/json, text/plain, */*',
'Content-Type': 'application/json'
},
body: 'json=' + encodeURIComponent(JSON.stringify(json.json)) + '&delay=' + json.delay
})
.then((response) => {if(response.ok){alert("the call works ok")}})
.catch (function (error) {
console.log('Request failed', error);
});

// extend FormData for direct use of js objects
Object.defineProperties(FormData.prototype, {
load: {
value: function (d) {
for (var v in d) {
this.append(v, typeof d[v] === 'string' ? d[v] : JSON.stringify(d[v]));
}
}
}
})
var F = new FormData;
F.load({A:1,B:2});
fetch('url_target?C=3&D=blabla', {
method: "POST",
body: F
}).then( response_handler )

you can use fill-fetch, which is an extension of fetch. Simply, you can post data as below:
import { fill } from 'fill-fetch';
const fetcher = fill();
fetcher.config.timeout = 3000;
fetcher.config.maxConcurrence = 10;
fetcher.config.baseURL = 'http://www.github.com';
const res = await fetcher.post('/', { a: 1 }, {
headers: {
'bearer': '1234'
}
});

axios - send form data AND non-form data

I'm using axios to send data to my nodejs/express server. If I want to send form data, I do the following (and it works fine):
const formData = new FormData();
formData.append('nameOfFile', the_file);
axios({
method: 'post',
url: '/someRoute',
data: formData
headers: {
'Content-Type': 'multipart/form-data'
}
}).then(response => {
// Do something with response
}).catch(err => {
// Do something with err
});
Again, the above code works fine. Here is the /someRoute endpoint that it goes to:
app.post('/someRoute', (req, res) => {
const uploadedFile = req.files.nameOfFile;
res.send('success'):
});
The endpoint always successfully receives the file. So far, so good.
If I want to send some other piece of data, like a date, I can send it like so (and it also works):
const date = '2012-02-13';
axios({
method: 'post',
url: '/someRoute',
data: date
})
app.post('/someRoute', (req, res) => {
const date = req.body.date;
res.send('success'):
});
But how do I send both the formDate and date data? I tried the following (but it doesn't work):
const formData = new FormData();
formData.append('nameOfFile', the_file);
axios({
method: 'post',
url: '/someRoute',
data: {
form: formData,
date: '2012-02-13'
},
headers: {
'Content-Type': 'multipart/form-data'
}
}).then(response => {
// Do something with response
}).catch(err => {
// Do something with err
});
And the endpoint:
app.post('/someRoute', (req, res) => {
const uploadedFile = req.files.nameOfFile;
const date = req.body.date;
res.send('success'):
});
This gives me a 500 ERROR.

You can do the same thing you already did, just append the other data you also want to send to formData..
So
formData.append(‘date’, date);

Can't send correct JSON params from admin-on-rest (reactJS)

Hi all I'm following this https://marmelab.com/admin-on-rest/index.html, for login thing, I'm following https://marmelab.com/admin-on-rest/Authentication.html :
import { AUTH_LOGIN } from 'admin-on-rest';
import restClient from './restClient';
export default (type, params) => {
if (type === AUTH_LOGIN) {
const { username, password } = params;
const request = new Request('http://localhost:9000/login', {
method: 'POST',
headers: new Headers({"Content-Type": "application/json"}),
body: JSON.stringify({ username: username,
password: password})
})
return fetch(request)
.then(response => {
if (response.status < 200 || response.status >= 300) {
throw new Error(response.statusText);
}
return response.json();
})
.then(({ token }) => {
localStorage.setItem('token', token)
});
}
return Promise.resolve();
}
For API I'm using Rails 5.0, when running the code above and debug the params on API side I can't get params body, here is the result :
<ActionController::Parameters {"controller"=>"sessions", "action"=>"create"} permitted: false>
I tried to change sent headers (Content-Type) request to :
...
headers: new Headers({"Accept": "application/json",
"Content-Type": "application/x-www-form-urlencoded"}),
...
And debug the params again on API side, and the result :
<ActionController::Parameters {"{\"username\":\"jhon\",\"password\":\"dow\"}"=>nil, "controller"=>"sessions", "action"=>"create"} permitted: false>
So how to make getting params such :
ActionController::Parameters {"username"=>"jhon", "password"=>"doe", "controller"=>"sessions", "action"=>"create"} permitted: false>

By default browser takes form data if you want send json like format then ypu have to set json property true in API fetch method see below--
const request = new Request('http://localhost:9000/login', {
method: 'POST',
json: true,
headers: new Headers({"Content-type": "application/json"}),
body: JSON.stringify({ username: username,
password: password})
})

If you wish the json to interprete your characters, you should add the charset=utf-8 to parse.
const request = new Request('http://localhost:9000/login', {
method: 'POST',
body: JSON.stringify({ username, password }),
headers: new Headers({ 'Content-Type': 'application/json; charset=utf-8',
'Accept': 'application/json'
}),
})
And be sure you are saving the token correctly. For me I didn't use the token as the admin-on-rest suggested, I used a response Header named access-token, so I saved on localStorage directly in the response. Maybe that will influence the result on your code.
return fetch(request)
.then(response => {
if (response.status < 200 || response.status >= 300) {
throw new Error(response.statusText);
}
localStorage.setItem('access-token', response.headers.get('access-token'));
return response.json();
});