Hungry Machine

Since all canvas page views are proxied through POSTs, resource routes were hopelessly broken. The Facebook platform team was kind enough to add a new feature just for us rails folks: a new signed parameter that indicates the original request type (i.e. POST v. GET) against canvas pages.



Here’s a small patch you can stick at the end of environment.rb to restore REST-ful routes.

class ActionController::Routing::RouteSet
  def extract_request_environment(request)
    contents = request.body.read
    facebook_method_override = nil
    if contents =~ /fb_sig_request_method=([A-Z]+)/
      facebook_method_override = $1
    end
    request.body.string = contents
    { :method => facebook_method_override ? facebook_method_override.downcase.intern : request.method}
  end
end

UPDATE: Here’s a slightly better implementation that allows the .get? and .post? helpers as well as a few other things to work (thanks Chris Nolan for reminding us to update this blog entry):

ActionController::AbstractRequest.class_eval do
  def request_method_with_facebook_overrides
    @request_method ||= begin
      case
        when parameters[:_method]
          parameters[:_method].downcase.to_sym
        when parameters[:fb_sig_request_method]
          parameters[:fb_sig_request_method].downcase.to_sym
        else
          request_method_without_facebook_overrides
      end
    end
  end
  alias_method_chain :request_method, :facebook_overrides
end