feature11. Create a Facebook Application by using your ‘Facebook Developer account’
2. Get the ‘App ID’ and ‘App Secret’ of your created application

Add following gems to your Gemfile

  • gem ‘omniauth’
  • gem ‘omniauth-facebook’

Run ‘bundle install’

Create a middleware file named ‘omniauth.rb’ in ‘config/initializers’ path

Rails.application.config.middleware.use OmniAuth::Builder do
provider :facebook, ENV['FACEBOOK_KEY'], ENV['FACEBOOK_SECRET'],
{:scope ≥ 'email, read_stream, read_friendlists, friends_likes, friends_status, offline_access, publish_stream'}
end

This will hold the facebook_app_key and facebook_secret_key with permissions

Set your custom callback url in routes

match '/auth/:provider/callback', :to ≥ 'sessions#create' match '/auth/failure', :to ≥ 'sessions#failure'

Write the following codes in the Sessions Controller

def create
auth_hash = request.env['omniauth.auth'] # Got The precise information from facebook
if  !auth_hash.nil?
@user = User.find_or_create_from_auth_hash(auth_hash)
self.current_user = @user
redirect_to '/'
end
end
def failure
flash[:notice] = "Sorry, but you didn't allow access to our app!"
redirect_to '/'
end

Write the following code in your view page. You can use a custom image for the Facebook like ‘facebook.png’.

<%=link_to image_tag('/images/facebook.png'),
"/auth/facebook" %>