Facebook Page Tab App Is Blank?

Facebook page and canvas apps with Rails 4, can lead to a blank white page. In Rails 4, the X-Frame-Options are sets by default, and you should override them, to allow iframes in Rails.

class FacebookClubsController < ApplicationController
  layout "facebook_canvas"

  after_filter :allow_iframe

  def index
  end

  private

  def allow_iframe
    response.headers["X-Frame-Options"] = "GOFORIT"
  end
end

https://gist.github.com/shavit/5171168

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