OAuth for Google Apps

client.rb

#lib/google/client.rb
require 'oauth'
require 'rexml/document'

module Google

  class Client
    attr_accessor :oauth_token
    attr_accessor :version

    def self.get(base, query_parameters, version = '2.0')
      make_request(:get, url(base, query_parameters), version)
    end

    private

    def self.make_request(method, url, version)
      oauth_consumer = OAuth::Consumer.new(GOOGLE_APP_ID, GOOGLE_APP_SECRET)
      access_token = OAuth::AccessToken.new(oauth_consumer)

      response = access_token.request(method, url, {'GData-Version' => version})
      if response.is_a?(Net::HTTPFound)
        return make_request(method, response['Location'], version)
      end
      return unless response.is_a?(Net::HTTPSuccess)
      feed = REXML::Document.new(response.body)
      throw :halt, [500, "Unable to query feed"] if feed.nil?
      feed
    end

    def self.url(base, query_parameters={})
      url = base
      unless query_parameters.empty?
        url += '?'
        query_parameters.each { |key, value| url += "#{CGI::escape(key)}=#{CGI::escape(value)}&" }
        url.chop!
      end
      url
    end
  end
end

contact.rb

#lib/google/contact.rb
module Google
  class Contact
    attr_accessor :full_name, :first_name, :last_name, :email, :company, :title, :notes

    def self.all(email)
      feed = Google::Client.get("https://www.google.com/m8/feeds/contacts/default/full", {
          'xoauth_requestor_id' => email
      }, '3.0')

      feed.elements.collect('//entry') do |entry|
        new(
            :full_name => entry.elements["gd:name"].elements["gd:fullName"].text,
            :first_name => entry.elements["gd:name"].elements["gd:givenName"].text,
            :last_name => entry.elements["gd:name"].elements["gd:familyName"].text,
            :email => entry.elements["gd:email"].attribute("address").value,
            :company => entry.elements["gd:organization"].elements["gd:orgName"].text,
            :title => entry.elements["gd:organization"].elements["gd:orgTitle"].text,
            :notes => entry.elements["content"].text
        )
      end
    end

    def initialize(options = {})
      @full_name = options[:full_name]
      @first_name = options[:first_name]
      @last_name = options[:last_name]
      @email = options[:email]
      @company = options[:company]
      @title = options[:title]
      @notes = options[:notes]
    end
  end
end

Gemfile

source 'https://rubygems.org'

...
gem 'oauth'
gem 'omniauth-openid'
gem 'omniauth-google-apps'
...

omniauth.rb

#config/initializers/omniauth.rb
require 'openid/store/filesystem'

Rails.application.config.middleware.use OmniAuth::Builder do
  provider :google_apps, :store => OpenID::Store::Filesystem.new('./tmp')
end

sessions_controller.rb

#app/controllers/sessions_controller.rb
class SessionsController < ApplicationController
  skip_before_filter :authenticate_user!, only: :create

  def create
    auth = request.env["omniauth.auth"]
    user = User.find_by_uid(auth["uid"]) || User.create_with_omniauth(auth)
    session[:user_id] = user.id
    redirect_to root_url, :notice => "Signed in!"
  end

  def destroy
    session[:user_id] = nil
    redirect_to root_url, :notice => "Signed out!"
  end
end

user.rb

#lib/google/user.rb
module Google
  class User
    attr_accessor :login, :first_name, :last_name
    def self.all(domain)
      feed = Google::Client.get("https://apps-apis.google.com/a/feeds/#{domain}/user/2.0", {
          'get' => 'all'
      })
      feed.elements.collect('//entry') { |e| new_from_entry(e) }
    end

    def self.find(domain, login)
      feed = Google::Client.get("https://apps-apis.google.com/a/feeds/#{domain}/user/2.0/#{login}", {})
      feed.elements.collect('//entry') { |e| new_from_entry(e) }
    end

    def initialize(options ={})
      @login = options[:login]
      @first_name = options[:first_name]
      @last_name = options[:last_name]
    end

    private

    def self.new_from_entry(entry)
      new(
          :login => entry.elements["apps:login"].attribute("userName").value,
          :first_name => entry.elements["apps:name"].attribute("givenName").value,
          :last_name => entry.elements["apps:name"].attribute("familyName").value,
      )
    end
  end
end

Deprecated. Please see the fork under my account https://gist.github.com/TildeWill/5078443