Easy Koala (FB) integration with Rails 3

_fbinit.html.erb

#
#  app/views/shared/_fbinit.html.erb
#

<div id="fb-root"></div>
<!--  Facebook -->
<script>
 window.fbAsyncInit = function() {
   FB.init({
     appId  : '<%= Facebook::APP_ID %>',
     status : true, // check login status
     cookie : true, // enable cookies to allow the server to access the session
     channelUrl : '<%= Facebook::CALLBACK_URL %>/channel.html',
     xfbml  : true  // parse XFBML
   });
   
   // logout if FB flag is set
   if ( typeof(FB_LOGOUT_FLAG) != 'undefined' )
       FB.logout( function(response){ location.href = "/"; } );
   
   // Browser-specific hacks to make FB Connect more reliable
   $.browser.chrome = /chrome/.test(navigator.userAgent.toLowerCase());
   if ($.browser.chrome || $.browser.msie) {
     FB.XD._origin = window.location.protocol + "//" + document.domain + "/" + FB.guid();
     FB.XD.Flash.init();
     FB.XD._transport = "flash";
   } else if ($.browser.opera) {
     FB.XD._transport = "fragment";
     FB.XD.Fragment._channelUrl = window.location.protocol + "//" + window.location.host + "/";
   }
}; 
  
(function() {   
    var e = document.createElement('script'); 
    e.async = true;
    e.src = document.location.protocol + '//connect.facebook.net/en_US/all.js';
    document.getElementById('fb-root').appendChild(e);

}());

</script>

application_controller.rb

#
# /app/controllers/application_controller.rb
#

before_filter :load_user

def load_user  

  #set facebook + session vars
  @fb_oauth = Koala::Facebook::OAuth.new  	
  @fb_graph = Koala::Facebook::API.new  # can only access public datam, temporary.
  session[:fb_id] ||= @fb_oauth.get_user_from_cookies(cookies)

  begin
    #if user is logged in
    if session[:fb_id]

      #Grab their access token, and upgrade the graph object
      if @fb_oauth.get_user_info_from_cookies(cookies)
        token = @fb_oauth.get_user_info_from_cookies(cookies)["access_token"]
        @fb_graph = Koala::Facebook::API.new( token )
      end

      #load existing user from DB if possible
      @current_user = User.where( :facebook_id => session[:fb_id] ).first

      #otherwise create new user
      if !@current_user
        fb_obj = @fb_graph.get_object( session[:fb_id] )
        @current_user = User.newFromFB( fb_obj )
      end

    end

  rescue Koala::Facebook::APIError
    #User cookie is stale, so don't act like they are logged in
    session.clear
  end

end

channel.html

#
# /public/channel.html
#
<script src="http://connect.facebook.net/en_US/all.js"></script>

facebook.js

#
# /assets/javascript/[controller].js
# [ whatever javascript file is associated with the above view... ]
#

/*----------------------------------------------------------------------------------------
Splash Page
------------------------------------------------------------------------------------------*/
$(document).ready( function() {

  //Facebook Login Code
  fb_connect($("#fb_login"), loginSuccess);

});

function loginSuccess() { 
   alert("logged in successfully, hooray!");
}


function fb_connect(obj, success_function) {
  var click_fn = function() {
    $(this).find("span.button-text").html("Logging you in...");

    FB.login( function(response){
        console.log(response);
        if (response.status === "connected") {
            success_function.call(obj);
        } else {
          // user is not logged in
          $(this).find("span").html("Connect with Facebook");
          alert('Facebook login failed, please try again!');
        }
      }, {scope:''} // add PERMISSIONS HERE
                    // via: https://developers.facebook.com/docs/authentication/permissions/
    );
  }
  $(obj).click(click_fn);
}

facebook.scss

#
# /assets/stylesheets/[controller].css.scss
# [ whatever scss file is associated with the above view... ]
#

#fb_connect{
    width: 208px;
    margin-left: auto;
    margin-right: auto;
    margin-top: 30px;
}
#privacy_info {
    color: #888;
    font-size: 11px;
    margin-top: 15px;
    a{
        color: #888;
        &:hover{
            text-decoration:underline;
        }
    }
}

.facebook-button {
     height: 46px;
     width:160px;
     display: block;
     background: transparent image-path("facebook-lg-f.png") no-repeat top left;
     padding-left: 48px;
     cursor: pointer;

     .button-text {
         display: block;
         padding: 15px 7px 17px 5px;
         background: transparent image-path("facebook-lg-r.png") no-repeat top right;
         color: #888;
     }
}

facebook.yml

# 
# config/facebook.yml
# [ sign up for an app at facebook.com/developers ]
#

development:
  app_id: 
  secret_key: 
  callback_url: 
 
production:
  app_id: 
  secret_key: 
  callback_url: 
  

Gemfile

#
# don't forget to run bundle install :)
#
gem 'koala'

index.html.erb

#
# /app/views/controller/index.html.erb
# [ whatever file you want to add FB login to ]
#


<div id='fb_connect'>
	<div id='fb_login' class='facebook-button large'><span class='button-text'>Login!</span></div>
	<p id='privacy_info'>Questions? Read our <a href='/privacy'>Privacy Policy</a></p>
</div>

<!-- FB partial settings -->
<%= render :partial => 'shared/fbinit'%>

koala.rb

# 
# config/initializers/koala.rb
#

module Facebook
 CONFIG = YAML.load_file(Rails.root.join("config/facebook.yml"))[Rails.env]
 APP_ID = CONFIG['app_id']
 SECRET = CONFIG['secret_key']
 CALLBACK_URL = CONFIG['callback_url']
end

Koala::Facebook::OAuth.class_eval do
  
 def initialize_with_default_settings(*args)
   case args.size
      when 0, 1
          raise "application id and/or secret are not specified in the config" unless Facebook::APP_ID && Facebook::SECRET
          initialize_without_default_settings(Facebook::APP_ID.to_s, Facebook::SECRET.to_s, Facebook::CALLBACK_URL.to_s)
      when 2, 3
          initialize_without_default_settings(*args)
    end
 end

 alias_method_chain :initialize, :default_settings
end

user.rb

#
# /app/models/user.rb
#

def self.newFromFB(fb_user)
  user = User.new
  user.facebook_id = fb_user["id"]
  user.name = fb_user["first_name"] + " " + fb_user["last_name"]
  user.age = self.age_from_bday_string(fb_user["birthday"])
  user.gender = fb_user["gender"]
  user.save
  user
end