json_hax.rb

class JsonHax
                 
  def initialize(app)
    @app = app
  end  

  def call(env)
    if env['CONTENT_TYPE'] == 'application/json'
      env['CONTENT_TYPE'] = 'application/xml'
      env['REQUEST_URI'].gsub!(/\.json/, '.xml')
      env['PATH_INFO'].gsub!(/\.json/, '.xml')
      
      status, headers, body = @app.call(env)      
      
      if headers['Content-Type'] =~ /application\/xml/
        body_string = ''
        body.each { |s| body_string << s }
      
        body = Hash.from_xml(body_string).to_json
        headers['Content-Type']   = 'application/json'
        headers['Content-Length'] = body.length.to_s      
      end
      
      return [status, headers, body]
    end

    @app.call(env)
  end
  
end