Axios doesn't send cookies with POST and data

Summary

I was beating my head off of the issue reported in #191 for awhile but then I noticed something. Post requests WITHOUT data work fine. Post requests WITH data seem to overwrite some config settings.

#### Context

Specifically for me, all my AJAX requests (which are CORS-protected) need a cookie to get past my authentication provider. Given that, I had set withCredentials to true in my axios instance. Everything was fine for GET and data-less POST requests. But as soon as I tried to post some data, I got hit with CORS errors again. Upon inspection, for some reason Axios stops sending the cookie header (and thus the auth token) when I specify data. The lack of the cookie means the server rejects the request (returning a 302 in my case) which the browser reports as a CORS failure, oddly enough.

I saw the message from @mike-robertson on #191 about using json.stringify. However, my data must be urlencoded. I used the query-string package to encode the parameters directly. It worked after that!

In summary, given:

import axios from 'axios';
import queryString from 'query-string';

const api = axios.create({
	withCredentials: true
});

params = {
   foo: 'bar',
   baz: 3
};

then the following will not send the cookie header.

api.post('bluh', params);

but these will:

api.post('bluh');
api.post('bluh', queryString.stringify(params));

This seems like a pretty major problem and should at least be mentioned in the docs.

• axios version: v0.16.1
• Environment: node v7.6.0 on KDE Neon
• Chrome info:

Google Chrome	58.0.3029.81 (Official Build) (64-bit)
Revision	ac0bae59f0aa5b391517e132bf172144b1939333-refs/branch-heads/3029@{#746}
OS	Linux
JavaScript	V8 5.8.283.32

[jaspersorrio]

I had the same problem with post not sending cookies!

I solved my problem by doing

axios("http://mysite.com/api/things/", {
  method: "post",
  data: someJsonData,
  withCredentials: true
})

[toyflish]

I had a similar issue, doing a a post-request same origin axios with default configuration sent the auth-cookie, same setup as cors from other domain axios did not send the auth-cookie until I set the configuration to axios.defaults.withCredentials = true. Would be better to have same behaviour on both types of request.