Facebook Canvas application with Rails 3: Detect if user is a fan

Hello and excuse me again

I am trying to know if user in my canvas application is fan or not. I am working with Rails 3 with fbgraph gem.

So in my controller I try:

def find_auth
    if params.has_key? :signed_request
      session[:signed_request] = params[:signed_request]
      @auth = authorizor.from_signed_request params[:signed_request]
decode_signed_request =     Canvas.parse_signed_request(configatron.fb_authentication_app_secret, params[:signe开发者_Python百科d_request])
    else
      @auth = authorizor.from_signed_request session[:signed_request]
    end
  end

  def authorizor
    FbGraph::Auth.new(configatron.fb_authentication_app_key, configatron.fb_authentication_app_secret)
  end

however decode_signed_request haven´t got page data only is a hash with 3 elements:

Algorithm
User(age,country and locale)
issued_at

Depending if the user is fan or not i should render a page or another. If the user is fan show the main content, else i should render a page with a like button. If the user click "like" I should ask for permission in a popup.

Thanks in advance. If you need more information please to comment.

I can solve my problem. In a canvas application this need permissions. However in tab application when i parsed params[:signed_request] exist a key with like information.