Authlogic OAuth

Authlogic OAuth is an extension of the Authlogic library to add OAuth support. One use case for authentication with OAuth is allowing users to log in with their Twitter credentials.

Helpful links

• Authlogic: github.com/binarylogic/authlogic
• OAuth Example Project: github.com/jrallison/authlogic_example/tree/with-oauth
• Live example with Twitter: authlogic-oauth.heroku.com

Install and use

1. Install Authlogic and setup your application

• Authlogic: github.com/binarylogic/authlogic
• Authlogic Example: github.com/binarylogic/authlogic_example

2. Install OAuth and Authlogic_Oauth

  $ sudo gem install oauth
  $ sudo gem install authlogic-oauth

Now add the gem dependencies in your config:

  config.gem "oauth"
  config.gem "authlogic-oauth", :lib => "authlogic_oauth"

Or for older version of rails, install it as a plugin:

  $ script/plugin install git://github.com/jrallison/authlogic_oauth.git

3. Make some simple changes to your database:

  class AddUsersOauthFields < ActiveRecord::Migration
    def self.up
      add_column :users, :oauth_token, :string
      add_column :users, :oauth_secret, :string
      add_index :users, :oauth_token

      change_column :users, :login, :string, :default => nil, :null => true
      change_column :users, :crypted_password, :string, :default => nil, :null => true
      change_column :users, :password_salt, :string, :default => nil, :null => true
    end

    def self.down
      remove_column :users, :oauth_token
      remove_column :users, :oauth_secret

      [:login, :crypted_password, :password_salt].each do |field|
        User.all(:conditions => "#{field} is NULL").each { |user| user.update_attribute(field, "") if user.send(field).nil? }
        change_column :users, field, :string, :default => "", :null => false
      end
    end
  end

4. Make sure you save your objects properly

You only need to save your objects this way if you want the user to authenticate with their OAuth provider.

That being said, you probably want to do this in your controllers. You should do this for BOTH your User objects and UserSession objects (assuming you are authenticating users). It should look something like this:

  @user_session.save do |result|
    if result
      flash[:notice] = "Login successful!"
      redirect_back_or_default account_url
    else
      render :action => :new
    end
  end

You should save your @user objects this way as well, because you also want the user to authenticate with OAuth.

Notice we are saving with a block. Why? Because we need to redirect the user to their OAuth provider so that they can authenticate. When we do this, we don’t want to execute that block of code, because if we do, we will get a DoubleRender error. This lets us skip that entire block and send the user along their way without any problems.

5. Define the oauth_consumer class method on your UserSession model

The oauth_consumer should return an OAuth::Consumer which is configured for your OAuth provider. Here’s an example for Twitter:

  class UserSession < Authlogic::Session::Base

    def self.oauth_consumer
      OAuth::Consumer.new("TOKEN", "SECRET",
      { :site=>"http://twitter.com",
        :authorize_url => "http://twitter.com/oauth/authenticate" })
    end

  end

6. Add login and register buttons to your views

  <%= oauth_register_button :value => "Register with Twitter" %>
  <%= oauth_login_button :value => "Login with Twitter" %>

That’s it! The rest is taken care of for you.

Here are some next steps for the plugin.

1. Safe OAuth error handling.
2. Remove oauth request from the Rails request cycle.