OmniAuth Facebook  

Facebook OAuth2 Strategy for OmniAuth.

Supports OAuth 2.0 server-side and client-side flows. Read the Facebook docs for more details: http://developers.facebook.com/docs/authentication

Installing

Add to your Gemfile:

gem 'omniauth-facebook'

Then bundle install.

Usage

OmniAuth::Strategies::Facebook is simply a Rack middleware. Read the OmniAuth docs for detailed instructions: https://github.com/intridea/omniauth.

Here's a quick example, adding the middleware to a Rails app in config/initializers/omniauth.rb:

Rails.application.config.middleware.use OmniAuth::Builder do
  provider :facebook, ENV['FACEBOOK_KEY'], ENV['FACEBOOK_SECRET']
end

See the example Sinatra app for full examples of both the server and client-side flows (including using the Facebook Javascript SDK).

Configuring

You can configure several options, which you pass in to the provider method via a Hash:

For example, to request email, user_birthday and read_stream permissions and display the authentication page in a popup window:

Rails.application.config.middleware.use OmniAuth::Builder do
  provider :facebook, ENV['APP_ID'], ENV['APP_SECRET'],
    scope: 'email,user_birthday,read_stream', display: 'popup'
end

API Version

OmniAuth Facebook uses versioned API endpoints by default (current v2.6). You can configure a different version via client_options hash passed to provider, specifically you should change the version in the site and authorize_url parameters. For example, to change to v3.0 (assuming that exists):

use OmniAuth::Builder do
  provider :facebook, ENV['APP_ID'], ENV['APP_SECRET'],
    client_options: {
      site: 'https://graph.facebook.com/v3.0',
      authorize_url: "https://www.facebook.com/v3.0/dialog/oauth"
    }
end

Per-Request Options

If you want to set the display format, auth_type, or scope on a per-request basis, you can just pass it to the OmniAuth request phase URL, for example: /auth/facebook?display=popup or /auth/facebook?scope=email.

Auth Hash

Here's an example Auth Hash available in request.env['omniauth.auth']:

{
  provider: 'facebook',
  uid: '1234567',
  info: {
    email: 'joe@bloggs.com',
    name: 'Joe Bloggs',
    first_name: 'Joe',
    last_name: 'Bloggs',
    image: 'http://graph.facebook.com/1234567/picture?type=square',
    urls: { Facebook: 'http://www.facebook.com/jbloggs' },
    location: 'Palo Alto, California',
    verified: true
  },
  credentials: {
    token: 'ABCDEF...', # OAuth 2.0 access_token, which you may wish to store
    expires_at: 1321747205, # when the access token expires (it always will)
    expires: true # this will always be true
  },
  extra: {
    raw_info: {
      id: '1234567',
      name: 'Joe Bloggs',
      first_name: 'Joe',
      last_name: 'Bloggs',
      link: 'http://www.facebook.com/jbloggs',
      username: 'jbloggs',
      location: { id: '123456789', name: 'Palo Alto, California' },
      gender: 'male',
      email: 'joe@bloggs.com',
      timezone: -8,
      locale: 'en_US',
      verified: true,
      updated_time: '2011-11-11T06:21:03+0000',
      # ...
    }
  }
}

The precise information available may depend on the permissions which you request.

Client-side Flow with Facebook Javascript SDK

You can use the Facebook Javascript SDK with FB.login, and just hit the callback endpoint (/auth/facebook/callback by default) once the user has authenticated in the success callback.

Note that you must enable cookies in the FB.init config for this process to work.

See the example Sinatra app under example/ and read the Facebook docs on Login for JavaScript for more details.

How it Works

The client-side flow is supported by parsing the authorization code from the signed request which Facebook places in a cookie.

When you call /auth/facebook/callback in the success callback of FB.login that will pass the cookie back to the server. omniauth-facebook will see this cookie and:

1. parse it,
2. extract the authorization code contained in it
3. and hit Facebook and obtain an access token which will get placed in the request.env['omniauth.auth']['credentials'] hash.

Token Expiry

The expiration time of the access token you obtain will depend on which flow you are using.

Client-Side Flow

If you use the client-side flow, Facebook will give you back a short lived access token (~ 2 hours).

You can exchange this short lived access token for a longer lived version. Read the Facebook docs for more information on exchanging a short lived token for a long lived token.

Server-Side Flow

If you use the server-side flow, Facebook will give you back a longer lived access token (~ 60 days).

Supported Rubies

• Ruby MRI (1.9.3+)
• JRuby (1.9 mode)
• RBX (2.1.1+)

License

Copyright (c) 2012 by Mark Dodwell

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.