stub for linking with and posting to facebook from rails apps

facebook_account.rb

class FacebookAccount < ActiveRecord::Base

  # Stubbed out! Does no (good) error checking!  

  # Get these from facebook!
  FACEBOOK_CLIENT_ID = 'it'
  FACEBOOK_CLIENT_SECRET = 'secret'

  def authorize_url(callback_url = '')
    if self.oauth_authorize_url.blank?
      self.oauth_authorize_url = "https://graph.facebook.com/oauth/authorize?client_id=#{FACEBOOK_CLIENT_ID}&redirect_uri=#{callback_url}&scope=offline_access,publish_stream"
      self.save!
    end
    self.oauth_authorize_url
  end
  
  def validate_oauth_token(oauth_verifier, callback_url = '')
    response = RestClient.get 'https://graph.facebook.com/oauth/access_token', :params => {
                   :client_id => FACEBOOK_CLIENT_ID,
                   :redirect_uri => callback_url.html_safe,
                   :client_secret => FACEBOOK_CLIENT_SECRET,
                   :code => oauth_verifier.html_safe
                }
    pair = response.body.split("&")[0].split("=")
    if (pair[0] == "access_token")
      self.access_token = pair[1]
      response = RestClient.get 'https://graph.facebook.com/me', :params => { :access_token => self.access_token }
      self.stream_url = JSON.parse(response.body)["link"]
      self.active = true
    else 
      self.errors.add(:oauth_verifier, "Invalid token, unable to connect to facebook: #{pair[1]}")
      self.active = false
    end
    self.save!
  end
  
  def post(message)
    RestClient.post 'https://graph.facebook.com/me/feed', { :access_token => self.access_token, :message => message }
  end

end

facebook_accounts_controller.rb

class FacebookAccountsController < ApplicationController

  # Stubbed out! Does no (good) error checking!

  def new
    facebook_account = FacebookAccount.create()
    redirect_to(facebook_account.authorize_url(facebook_callback_url(:id => facebook_account.id)))
  end

  def callback
    if params[:error_reason] && !params[:error_reason].empty?
      # We have a problem!
      redirect_to(:root, :notice => "Unable to activate facebook: #{params[:error_reason]}")
    elsif params[:code] && !params[:code].empty?
      # This is the callback, we have an id and an access code
      facebook_account = FacebookAccount.find(params[:id])
      facebook_account.validate_oauth_token(params[:code], facebook_callback_url(:id => facebook_account.id))
      redirect_to(:root, :notice => 'Facebook account activated!')
    end
  end

end

Gemfile

gem 'rest-client'
gem 'json'

routes.rb

resource :facebook_account
match '/callback/facebook/:id' => "facebook_accounts#callback", :as => :facebook_callback

table.rb

  create_table "facebook_accounts", do |t|
    t.integer  "user_id"
    t.boolean  "active",              :default => false
    t.text     "stream_url"
    t.text     "access_token"
    t.text     "oauth_authorize_url"

    t.datetime "created_at"
    t.datetime "updated_at"
  end

I have a problem with FacebookAccount.validate_oauth_token method. So I change it

  def validate_oauth_token(oauth_verifier, callback_url = '')
    response = RestClient.post "https://graph.facebook.com/oauth/access_token", client_id: FACEBOOK_CLIENT_ID, redirect_uri: callback_url, client_secret: FACEBOOK_CLIENT_SECRET, code: oauth_verifier

    pair = response.body.split("&")[0].split("=")
    if (pair[0] == "access_token")
      self.access_token = pair[1]
      response = RestClient.get 'https://graph.facebook.com/me', :params => { :access_token => self.access_token }
      self.stream_url = JSON.parse(response.body)["link"]
      self.active = true
    else 
      self.errors.add(:oauth_verifier, "Invalid token, unable to connect to facebook: #{pair[1]}")
      self.active = false
    end
    self.save!
  end