Omniauth is a simple rails gem that provides multi-authentication for web applications. For example, if you wanted to use have a facebook and twitter login for your app, Ominauth makes this easy to do. Omniauth Identity also makes it easy to add your own authentication, if a user didn’t want to use the other services. For this post, I’ll walk through adding Omniauth Identity to your rails app. This walkthrough assumes that you are currently not using any other Omniauth strategies (facebook, twiiter) yet, but provides the basics in case you add other strategies later.

This tutorial is based on Ryan Bates Railscast #304 http://railscasts.com/episodes/304-omniauth-identity

From terminal window run the following

>> rails g controller sessions
>> rails g model user provider:string uid:string name:string
>> rails g model identity name:string email:string password_digest:string
>> rake db:migrate
>> rails g controller identities

add the following to your Gemfile

gem ‘omniauth-identity’
gem ”bcrypt-ruby’, ‘~> 3.0.0’

Create omniauth.rb in config/initializers and add the below to the file

Rails.application.config.middleware.use OmniAuth::Builder do
provider :identity, on_failed_registration: lambda { |env|
IdentitiesController.action(:new).call(env)
}
end

Add the following to your Identity model, identity.rb

class Identity < OmniAuth::Identity::Models::ActiveRecord
validates_presence_of :name
validates_uniqueness_of :email
validates_format_of :email, :with => /^[-a-z0-9_+\.]+\@([-a-z0-9]+\.)+[a-z0-9]{2,4}$/i
end

Add to your User model, user.rb

class User < ActiveRecord::Base

def self.from_omniauth(auth)
find_by_provider_and_uid(auth[“provider”], auth[“uid”]) || create_with_omniauth(auth)
end

def self.create_with_omniauth(auth)
create! do |user|
user.provider = auth[“provider”]
user.uid = auth[“uid”]
user.name = auth[“info”][“name”]
end
end
end

Add the below to your Sessions Controller, sessions_controller.rb

class SessionsController < ApplicationController

def new
end

def create
user = User.from_omniauth(env[“omniauth.auth”])
session[:user_id] = user.id
render :text => ‘Signed in!’
end

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

def failure
render :text => params[:message]
end
end

Add to your Identities Controller, identities_controller.rb

class IdentitiesController < ApplicationController
def new
@identity = env[‘omniauth.identity’]
end
end

Add to routes.rb

resources :identities

root :to => ‘sessions#new’
match ‘/auth/:provider/callback’ => ‘sessions#create’
match ‘/signout’ => ‘sessions#destroy’, :as => :signout

match ‘auth/failure’ => ‘sessions#failure’

Under views/sessions, create new.html.erb and add the following

<%= form_tag “/auth/identity/callback” do %>
<div class=”field”>
<%= label_tag :auth_key, “Email” %><br>
<%= text_field_tag :auth_key %>
</div>
<div class=”field”>
<%= label_tag :password %><br>
<%= password_field_tag :password %>
</div>
<div class=”actions”><%= submit_tag “Login” %></div>
<% end %>
<%= link_to ‘New User Sign up’, new_identity_path %>

Under views/identities, create new.html.erb and add the following

<h3>New Account</h3>
<%= form_tag “/auth/identity/register” do %>
<% if @identity && @identity.errors.any? %>
<div class=”error_messages”>
<h2><%= pluralize(@identity.errors.count, “error”) %> prohibited this account from being saved:</h2>
<ul>
<% @identity.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>
<div class=”field”>
<%= label_tag :name %><br>
<%= text_field_tag :name, @identity.try(:name) %>
</div>
<div class=”field”>
<%= label_tag :email %><br>
<%= text_field_tag :email, @identity.try(:email) %>
</div>
<div class=”field”>
<%= label_tag :password %><br>
<%= password_field_tag :password %>
</div>
<div class=”field”>
<%= label_tag :password_confirmation %><br>
<%= password_field_tag :password_confirmation %>
</div>
<div class=”actions”><%= submit_tag “Register” %></div>
<% end %>