Rails + XMLHttpRequest#sendAsBinary() / missing file contents

Firefox, since version 3, has supported 'sendAsBinary()', a 'new file transfer' method on the XMLHttpRequest object. And in the latest Firefox beta also supports drag-and-drop.

There is some lovely sample code that combines these two features posted on the CSS.Ninja blog at:


But the author's code is designed to work with a minimal PHP demo app. So I thought that I would try to get a RoR version working.

The crux of the JavaScript code are these 5 lines

       var upload_file_url = // route to RoR application        var file = // some code to acquire the file        var xhr = new XMLHttpRequest()         xhr.open("POST", upload_file_url);         xhr.overrideMimeType('text/plain; charset=x-user-defined- binary');         xhr.sendAsBinary(file.getAsBinary());

Well this is all very fine, except that we normally have a line in application_controller.rb


Which means the server is now expecting an authenticity_token in all of the requests that it handles (unless specified otherwise)

So, when you execute ' xhr.sendAsBinary(file.getAsBinary())' the server rejects the request because there is no 'authenticity_token'.

Well, would it work to incorporate the authenticity_token, and any other useful file characteristics in the url? To find out, I defined a route in routes.rb like so:

map.file_upload '/ file_upload/:authenticity_token/:user_id/:md5/:name/:suffix/ create', :controller=>'uploaded_files', :action=>'create', :method=>'post'

And in the JavaScript I extract the authenticity_token from the page and incorporated it into the 'upload_file_url' along with the other interesting parameters.

And it works... sort of.

If I pretty-print out the params variable this I can see all of the attributes I incorporated into the URL

{"name"=>"les-amis2", "method"=>"post", "authenticity_token"=>   "8a576fa97709c92e102eb5da515481009e2bf5044caa2e014ef6004dde58f5c4", "action"=>"create", "user_id"=>"2", "suffix"=>"jpg", "md5"=>"1a8591455122cdb9ff1015d694c9c067", "controller"=>"uploaded_files"}

What is missing however is any reference to the file contents!!!!!!

Does anyone know where it is? I am using 'mongrel' on the server side, by the way.

Fred Obermann