Get list of facebook friends that are also using the application

gistfile1.rb

@participants = Participant.where("facebook_uid IN (?)", connected_friends).order('id DESC')

def connected_friends
  graph = Koala::Facebook::API.new(get_user_oauth_token)
  friends = graph.get_connections("me", "friends", fields: 'installed')
  friends.collect do |f|
    f["installed"] == true ? f["id"] : nil
  end.compact
rescue => e
  notify_honeybadger_or_ignore e
end