Posting JSON data problem with content type

I used the example provided on the readme file.

fetch('/users', {
  method: 'POST',
  headers: {
    'Accept': 'application/json',
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    name: 'Hubot',
    login: 'hubot',
  })
})

I got the following headers on devtools. The problem is marked with a “//” comment. content type is really not allowing us to set it to application/json, I have tried a 100 different ways.

As result I set up a simple node js server to see request.body (always is empty)

If I use curl http://localhost:3001/log -H 'Content-Type: application/json' -d '{"longUrl": "http://www.google.com/"}' this works fine. I can see the request.body

General
===
Request URL:http://localhost:3001/log
Request Method:POST
Status Code:200 OK
Remote Address:[::1]:3001

Response Headers
===
Connection:keep-alive
Content-Length:16
Content-Type:application/json; charset=utf-8
Date:Mon, 18 Apr 2016 10:04:14 GMT
ETag:W/"10-c2PoX+nt7m8FOksxlYjAhg"
X-Powered-By:Express

Request Headers
===
accept:application/json
Accept-Encoding:gzip, deflate
Accept-Language:en-GB,en;q=0.8,sq;q=0.6,it;q=0.4
Cache-Control:no-cache
Connection:keep-alive
Content-Length:32
content-type:text/plain;charset=UTF-8           //the problem//
Host:localhost:3001
Origin:http://xxxxxxxxxxxxxxx.co.uk
Pragma:no-cache
User-Agent:Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/49.0.2623.112 Safari/537.36

Request Payload
===
{name: "Hubot", login: "hubot"}
login
:
"hubot"
name
:
"Hubot"

[stavarengo]

@bo3en, the problem is that when you work in ‘mode’ ‘no-cors’, the Headers become an immutable and you will not be able to change some of its entries. One of the heads you can’t change is the Content-Type. When you set ‘mode’ to ‘no-cors’ you will be able to change only these headers:

• Accept
• Accept-Language
• Content-Language
• Content-Type and whose value, once parsed, has a MIME type (ignoring parameters) that is application/x-www-form-urlencoded, multipart/form-data, or text/plain

In another words, in ‘mode’ '-no-‘cors’ you can only set application/x-www-form-urlencoded, multipart/form-data, or text/plain to the Content-Type.

So the solution is stop using fetch or changing it to ‘cors’ ‘mode’. Of course this will only works if your server also accepts ‘cors’ requests.

Here is an example of how you could enable CORS in an Apache Server

SetEnvIfNoCase Access-Control-Request-Method "(GET|POST|PUT|DELETE|OPTIONS)" IsPreflight=1
SetEnvIfNoCase Origin ".*" AccessControlAllowOrigin=$0
SetEnvIfNoCase Origin "https://(url1.com|url2.com)$" AccessControlAllowOrigin=$0

Header always set Access-Control-Allow-Origin %{AccessControlAllowOrigin}e env=AccessControlAllowOrigin
Header always set Access-Control-Allow-Methods "GET, POST, PUT, DELETE, OPTIONS" env=IsPreflight
Header always set Access-Control-Allow-Headers "Content-Type, Authorization, Accept, Accept-Language" env=IsPreflight
Header always set Access-Control-Max-Age "7200" env=IsPreflight
RewriteCond %{REQUEST_METHOD} OPTIONS
RewriteCond %{ENV:IsPreflight} 1
RewriteRule ^(.*)$ $1 [R=204,L]

The above code will inject the CORS headers in the response when its necessary. With this code your server will allow CORS only from the the domains “url1.com” or “url2.com”.

Here are some references

• https://developer.mozilla.org/en-US/docs/Web/API/Request/mode
• https://fetch.spec.whatwg.org/#simple-header

[AlpeshMN]

I am still getting issue on using fetch call. It is changing “Content-Type” from ‘application/json’ to ‘text/plain;charset=UTF-8’ while i run this code. If someone faced same kind of issue.