Facebook oauth and api in Sinatra

iframe apps authentication with cookie problem workaround

here are the steps:

1. Render index page with JS SDK stuff: FB.init and FB.getLoginStatus - see index.erb

2. If getLoginStatus returns session, take signed_request from url and do top redirect outside facebook to yourapp.com/setcookie:

   line 16 of index.erb:

   top.location = "<%= APP_CONFIG['app_url'] %>/setcookie?signed_request="+jQuery.url.param("signed_request");

3. At yourapp.com/setcookie take signed_request from url and save it to cookie. Then redirect back to apps.facebook.com/your-app/iframe-dashboard. It actually happens so fast, that the FB chrome around the iframe doesn't even disappear and users won't notice they were redirected outside and back

   lines 19, 20 of fbsin.rb:

   session[:signed_request] = params[:signed_request] # just save parameter to cookie...

   redirect APP_CONFIG['fb_app_url']+"/iframe-dashboard"

4. At apps.facebook.com/your-app/iframe-dashboard you can now read the signed_request from cookie

5. And of course you can read it on any other page of your app without sending it in url params

FB oauth process without any SDK

In everyday life you would probably use JS/PHP/Python/Ruby SDK, but it's useful to see how it works underneath. Put your config to config.yml and you should be ready to go. There are explanatory comments throughout the code.

FB oauth process:

• server side authenticating as user ('/connect')
• JS SDK authentication on client side ('/js')

Publishing message:

• from server side through "old" rest api (POST to '/restapi')
• from server side through new graph api (POST to '/graphapi')
• from client side using JS SDK ('/js')
• from client side by displaying pre-filled modal window (using JS SDK as well) ('/js')

Feel free to reuse