Only Rails 3 is supported.

Uses fbgraph (github.com/nsanta/fbgraph) Could use the Oauth2 gem directly, but it is more than likely that you would want to use other features of facebook (ie post feed updates).

How to use

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Setup devise (github.com/plataformatec/devise), use Rails 3

Include the gem in Gemfile after devise:

gem 'devise'
gem 'devise_oauth2_facebook'

Include the ‘:devise_oauth2_facebook’ in your model:

devise :database_authenticatable, :registerable, :confirmable,
       :recoverable, :rememberable, :trackable, :validatable, :devise_oauth2_facebook

Add the following config options:

$ config/initializers/devise.rb

config.facebook_api_key = "KEY"
config.facebook_api_secret = "SECRET"
config.facebook_permissions = 'offline_access,email,publish_stream'

Good minimum to have is “offline_access,email”

Create a migration file to add the columns:

add_column :users, :facebook_uid, :string
add_column :users, :facebook_token, :string

Finally, update your view to include “Login with facebook” link:

<%= link_to "Login with facebook", user_fb_auth_path %>