.gems

# Heroku .gems file
oauth
nokogiri

application_controller.rb

class ApplicationController < ActionController::Base
  protected
  def initialize_user
    # If we have oauth_token and oauth_secret, we
    # can recreate the access token needed for
    # YouTube API communication on behalf of the
    # user
    if session[:oauth_token] && session[:oauth_secret]
      @access_token ||= OAuth::AccessToken.new(
                                consumer, 
                                session[:oauth_token], 
                                session[:oauth_secret])
    end
  end

  # This is the OAuth::Consumer we use to communicate
  # with Google
  def consumer
    @consumer ||= begin
      options = {
          :site => "https://www.google.com",
          :request_token_path => "/accounts/OAuthGetRequestToken",
          :access_token_path => "/accounts/OAuthGetAccessToken",
          :authorize_path=> "/accounts/OAuthAuthorizeToken"
        }
    
      OAuth::Consumer.new('YOUR KEY', 'YOUR SECRET', options)
    end
  end
end

environment.rb

RAILS_GEM_VERSION = '2.3.5' unless defined? RAILS_GEM_VERSION
require File.join(File.dirname(__FILE__), 'boot')

Rails::Initializer.run do |config|
  config.gem 'oauth'
  config.gem 'nokogiri'

  config.time_zone = 'UTC'
end

homepage_controller.rb

class HomepageController < ApplicationController
  before_filter :initialize_user

  def index
    # If we have the instance vaiable @access_token, then
    # we must assume we can use this to communicate with
    # the YouTube API on behalf of the logged in user.
    # 
    # Here we simply fetch her username so we can display
    # it in the view
    if @access_token
      body = @access_token.get("http://gdata.youtube.com/feeds/api/users/default").body
      @username = Nokogiri::XML.parse(body).search("author").children.first.text
    end
  end
end

index.html.erb

<h1>YouTube OAuth example</h1>
<% if @username %>
<p>You are logged in to this site via YouTube as <%= @username %>!</p>
<br><br>
<p><%= link_to 'Log out', :controller => :session, :action => :destroy %></p>
<% else %>
<%= link_to 'Log in via YouTube', :controller => :session, :action => :new %>
<% end %>

routes.rb

ActionController::Routing::Routes.draw do |map|
  map.root :controller => :homepage
  map.connect ':controller/:action/:id'
  map.connect ':controller/:action/:id.:format'
end

session_controller.rb

class SessionController < ApplicationController
  def new
    request_token = consumer.get_request_token(
      {:oauth_callback => "http://runeb-oauth.heroku.com/session/create" },
      {:scope => "http://gdata.youtube.com"})
    
    # Keep the secret
    session[:oauth_secret] = request_token.secret
    # Redirect to Google for authorization
    redirect_to request_token.authorize_url
  end

  # User authorized us at Google site
  def create
    # Recreate the (now authorized) request token
    request_token = OAuth::RequestToken.new(consumer, 
                                            params[:oauth_token],
                                            session[:oauth_secret])
    # Swap the authorized request token for an access token                                        
    access_token = request_token.get_access_token(
                      {:oauth_verifier => params[:oauth_verifier]})
    
    # Save the token and secret to the session
    # We use these to recreate the access token
    session[:oauth_token] = access_token.token
    session[:oauth_secret] = access_token.secret
    redirect_to "/"
  end
  
  def destroy
    # User logs out, forget the access token
    reset_session
    redirect_to '/'
  end
end