SWFUpload session cookie

flash_session_cookie_middleware.rb

require 'rack/utils'

class FlashSessionCookieMiddleware
  def initialize(app, session_key = '_session_id')
    @app = app
    @session_key = session_key
  end

  def call(env)
    if env['HTTP_USER_AGENT'] =~ /^(Adobe|Shockwave) Flash/
      params = ::Rack::Utils.parse_query(env['QUERY_STRING'])
      env['HTTP_COOKIE'] = [ @session_key, params[@session_key] ].join('=').freeze unless params[@session_key].nil?
      
      p [ @session_key, params[@session_key] ].join('=')
    end
    @app.call(env)
  end
end

post_param_for_SWFUpload.rb

def post_params_json
  post_params = {}
  post_params['authenticity_token'] = CGI::escape(form_authenticity_token)
  post_params[session_key.to_s] = CGI::escape(cookies[session_key])
  post_params.to_json
end

session_store.rb

ActionController::Base.session = {
  :key         => '_your_session',
  :secret      => 'your key'
}

ActionController::Dispatcher.middleware.use FlashSessionCookieMiddleware, ActionController::Base.session_options[:key]

upload.js.erb

$(function(){
  $(".swfuploader").swfuploader({
    upload_url      : "/images",
    set             :  "MultiFile",
    file_post_name  : "image[attachment]",
    post_param      : <%= post_params_json %>
    upload_success_handler : function(file, serverData, response){
      var data = eval("("+ serverData + ")");
      $(data.partial).hide().prependTo($(".images")).fadeIn();
    }
  })
});