OAuth with Koala

examples

GET http://localhost:3000/fb/fb_code
RESPONSE
{"redirect_url":"https://www.facebook.com/dialog/oauth?client_id=893637180663238\u0026redirect_uri=http%3A%2F%2Flocalhost%3A3000%2Ffb%2Fcallback"}

----
redirect to https://www.facebook.com/dialog/oauth?client_id=893637180663238\u0026redirect_uri=http%3A%2F%2Flocalhost%3A3000%2Ffb%2Fcallback
redirect to callback_url
GET http://localhost:3000/fb/callback?code=FB_AUTH_CODE
RESPONSE
{"access_token":"FB_ACCESS_TOKEN"}
----

GET http://localhost:3000/fb/fb_get_info?access_token=FB_ACCESS_TOKEN
RESPONSE
{"user_data":{"id":"4492344324865","email":"my_fake_email@gmail.com","first_name":"Roman","gender":"male","last_name":"Sotnikov","link":"https://www.facebook.com/app_scoped_user_id/4492344324865/","locale":"en_US","name":"Roman Sotnikov","timezone":6,"updated_time":"2015-05-18T05:19:54+0000","verified":true}}

facebook_controller.rb

class FbController < ApplicationController
  before_action :init_client, only: [:fb_code, :callback]
  def fb_code
    url = @koala.url_for_oauth_code
    render json: { redirect_url: url}
  end

  def fb_get_info
    data = Koala::Facebook::API.new(params[:access_token]).get_object("me")
    render json: { user_data: data }
  rescue Koala::Facebook::AuthenticationError => e
    render json: { status: :error, message: e.message }
  end

  def callback
    access_token = @koala.get_access_token(params[:code])
    render json: { access_token: access_token }
  end

  def init_client
    @koala ||= Koala::Facebook::OAuth.new(APP_KEY,
                                          APP_SECRET,
                                          "http://localhost:3000/fb/callback")
  end
end

initializers_koala.rb

APP_KEY = 123456789
APP_SECRET = "FooBarBaz"

routes.rb

AwesomeApp::Application.routes.draw do
  get "fb/callback"
  get "fb/fb_get_info"
  get "fb/fb_code"
  root 'index#index'
end

Please note that just an exampe and it completely untested.