Question

We are new to rails and are looking to use the Javascript SDK “Connect with Facebook” button on our homepage. Using this button in our app, we want to allow users to sign up for our site via Facebook, and be able to use their Facebook profile picture as their profile image for our web app.

What is the best way to implement this Facebook Connection with our Rails 3 app?

  devise_for :users

  resources :authentications

  resources :users do
      member do
        get :following, :followers
      end
  end
  resources :sessions,   :only => [:new, :create, :destroy]
  resources :microposts, :only => [:create, :destroy]
  resources :relationships, :only => [:create, :destroy]

  match '/signup',  :to => 'users#new'
  match '/signin',  :to => 'sessions#new'
  match '/signout', :to => 'sessions#destroy'
  match '/contact', :to => 'pages#contact'
  match '/home',   :to => 'pages#home'
  match '/help',    :to => 'pages#help'
  match '/feedback',    :to => 'pages#feedback'
  match '/privacy',    :to => 'pages#privacy'
  match '/terms',    :to => 'pages#terms'
  match '/',        :to => 'pages#home'

  resources :microposts

  resources :users
  resources :sessions, :only => [:new, :create, :destroy]


  root :to => 'pages#home'

  match "/auth/twitter/callback" => "sessions#omnicreate"
  match "/auth/facebook/callback" => "sessions#omnicreate"


end

SessionsController

class SessionsController < ApplicationController

  def new
    @title = "Sign in"
  end

  def create
      user = User.authenticate(params[:session][:email],
                           params[:session][:password])
      if user.nil?
        flash.now[:error] = "Invalid email/password combination."
        @title = "Sign in"
        render 'new'
      else
        sign_in user
        redirect_back_or user
      end
  end

  def destroy
        sign_out
        redirect_to root_path
  end
end

Answer 1

Looks like you need to do a couple things:

Change these lines in your routes file:

  root :to => 'pages#home'

  match "/auth/twitter/callback" => "sessions#omnicreate"
  match "/auth/facebook/callback" => "sessions#omnicreate"

To this:

  match "/auth/:provider/callback" => "sessions#omnicreate"

  root :to => 'pages#home' # this one should always be last

Both Twitter and Facbook are going to the same method so you will need to get that :provider param out later on to figure out if its Twitter or Facebook that sent them.

Next you need to create a method in your SessionsController that receives the callback like this:

def omnicreate

  data = request.env['omniauth.auth'] # here is all the user data
  if params[:provider] == 'twitter'
     #parse twitter data
  elsif params[:provider] == 'facebook'
     #parse fb data
  else
     # something is broken
     redirect_to '/404.html'
  end

  user = User.create! #use data you parsed to create a user
  redirect_to some_path, :notice => 'awwww yeah'
end

good luck!