Unable to send multipart/form data with POST requests.

[ripjar-mark]

In xhr level 2, now widely supported , the XMLHttpRequest.send method can be invoked with a formdata object, this will set the Content-Type header automatically to multipart/form-data; boundary=----WebKitFormBoundaryxxxxxxxxxxx.

Currently this library defaults the content type to application/x-www-form-urlencoded see net/xhr.js l104. Setting this causes xhr to not override the content-type header correctly and means that multipart/form-data cannot be sent with POST requests using this library.

Removing the default content-type fixes this.

[Senthil Padmanabhan]

@ripjar-mark Another option would be to set the content-type header as a part of header options when calling flow.

jsonpipe.flow(url, {
    "headers": { 
            "Content-Type": "multipart/form-data"
     }
})

Will this work?

[ripjar-mark]

Unfortunately, this stops XmlHttpRequest from setting the the boundary as above, making the request invalid.

[Senthil Padmanabhan]

Are you setting the data option as FormData in your case? In that scenario, will the below logic work

if (addContentHeader && Object.prototype.toString.call(options.data) !== '[object FormData]') {
    xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
}

[ripjar-mark]

Well, if you were allowing FormData then I believe you would also have to handle "Blob, BufferSource, FormData, URLSearchParams, ReadableStream, or USVString " source, there is more information about the behaviours of XHR and the way it sets the headers in the fetch spec

The alternative would be allowing users to set a flag which disables the override?

[Senthil Padmanabhan]

Is it possible for you to issue a PR with probably a disableContentType option? It may take a couple of days for me to get back to this project?