Match friends who are also using an app and see if they are also installed in the db.

match_friends.rb

  def match_friends
    # now just find the friends of the user who are also using the app.
    begin
      res = Bookface::Graph.request("fql", { :q=> "SELECT uid, name, pic_square FROM user WHERE is_app_user  AND uid IN (SELECT uid2 FROM friend WHERE uid1 = me())", :access_token => access_token })
    rescue
      res = nil
    end
    friend_ids = []
    # retrieve friend list from graph and compile a list of friends who are registered - aww friend
    unless res.nil? or res["data"].nil?
      res["data"].map do |friend|
        user = User.find_by_fbid(friend["uid"])
        friend_ids << user.id unless user.nil?
      end
    end
    # clear existing friends - aww NO friend
    Friendship.where("user_id = ? or friend_id = ?", self.id, self.id).destroy_all 
    # create friendships - aww NEW friend
    friend_ids.each do |friend_id|
      Friendship.create( { :user_id => self.id, :friend_id => friend_id } )  
    end
  end