Automatic Content-Type for FormData uploads

[nnarhinen]

When data passed to axios is of type FormData we have to let the browser
create the Content-Type header so that the boundaries will get right
etc.

Usage:

var data = new FormData();
data.append('field', 'some string');
data.append('file', someFile);

var opts = {
  transformRequest: function(data) { return data; }
};

axios.post('/fileupload', data, opts);

[nnarhinen]

@mzabriskie ping?

[mzabriskie]

@nnarhinen sorry for the delay, I have been overloaded lately. Your PR looks good.

[mzabriskie]

This is available with version 0.4.2

[powmedia]

This is working for me however the fact you need to implement a pass-through transformRequest() seems like an unnecessary step. If the library is detecting FormData anyway could it skip the need for this requirement?

[mzabriskie]

@powmedia there was a bug #53 that was causing this to be necessary. It is no longer needed.

[ppozniak]

Necro-posting, but still wonder why that happened, as per the spec it is possible to set up custom boundary for formdata.
Content-Type: multipart/form-data; boundary=something
https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Type#Syntax