Omniauth-Facebook callback does not get initialised in Rails Mountable Engine - ruby-on-rails

Question

I'm developing a mountable engine (called SimpleUser) which uses Devise, OmniAuth and OmniAuth-Facebook. First I made a test app with the gems about and every worked fine. Next, I started building the engine from scratch, using the code of the test app as an example.
Everything is almost done, except for the connection with Facebook (it uses the Javascript popup). When I click in "log in" the FB popup is displayed, I grant the app, it redirects to the route specified (see routes), but throws this error:
NoMethodError in SimpleUser::AuthController#create
undefined method `[]' for nil:NilClass
The error occurs in that action, in the line authentication = Authentication.find_by_provider_and_uid(auth['provider'], auth['uid']) where auth is nil (auth comes from auth = request.env["omniauth.auth"]).
One thing I check is that the Callback phase it's no initialised. This is the log of the test app:
Started GET "/auth/facebook/callback" for 127.0.0.1 at 2013-03-14
08:52:56 -0600 (facebook) Callback phase initiated. Processing by
AuthController#create as HTML Parameters: {"provider"=>"facebook"}
This is the log of the engine app:
Started GET "/simple_user/auth/facebook/callback" for 127.0.0.1 at 2013-03-14 08:51:19 -0600
Processing by SimpleUser::AuthController#create as HTML
Parameters: {"provider"=>"facebook"}
For manage OmniAuth, I added the gem to the .gemspec and to the Gemfile; also, I require the gems in the engine, and within a generator of the engine I move a template of omniauth.rb to config/initializers of the parent app during installation. This is what I have:
AuthController (located in app/controllers/simple_user/auth_controller.rb)
module SimpleUser
class AuthController < ApplicationController
def create
auth = request.env["omniauth.auth"]
authentication = Authentication.find_by_provider_and_uid(auth['provider'], auth['uid'])
if authentication
flash[:notice] = "Signed in successfully."
sign_in(:user, authentication.user)
redirect_to root_url
else
user = User.build_new_auth(auth)
#user.apply_omniauth(auth)
if user.save(:validate => false)
flash[:notice] = "Account created and signed in successfully."
sign_in(:user, user)
redirect_to root_url
else
flash[:error] = "Error while creating the user account. Please try again."
redirect_to root_url
end
end
end
end
end
Engine
module SimpleUser
require 'rubygems'
require 'devise'
require 'cancan'
require 'rolify'
require 'omniauth'
require 'omniauth-facebook'
require 'simple_form'
class Engine < ::Rails::Engine
isolate_namespace SimpleUser
config.before_configuration do
env_file = File.join(Rails.root, 'config', 'fb_config.yml')
YAML.load(File.open(env_file)).each do |key, value|
ENV[key.to_s] = value.to_s
end if File.exists?(env_file)
env_file = File.join(Rails.root, 'config', 'devise_config.yml')
YAML.load(File.open(env_file)).each do |key, value|
ENV[key.to_s] = value.to_s
end if File.exists?(env_file)
end
end
end
Generator
module SimpleUser
module Generators
class InstallGenerator < ::Rails::Generators::Base
source_root File.expand_path("../templates", __FILE__)
desc "Install SimpleUser"
def copy_config_file
copy_file "fb_config.yml", "config/fb_config.yml"
copy_file "devise_config.yml", "config/devise_config.yml"
copy_file "omniauth.rb", "config/initializers/omniauth.rb"
end
def copy_migrations
rake "simple_user:install:migrations"
SimpleUser::Engine.load_seed
end
end
end
end
Template of the omniauth.rb
require 'omniauth'
require 'omniauth-facebook'
OmniAuth.config.logger = Rails.logger
Rails.application.config.middleware.use OmniAuth::Builder do
provider :facebook, ENV['FACEBOOK_KEY'], ENV['FACEBOOK_SECRET'], :scope => ENV['FACEBOOK_SCOPE']
end
Routes (on engine)
match 'auth/:provider/callback', to: 'auth#create'
match 'auth/failure', to: redirect('/')
Routes (on dummy app)
mount SimpleUser::Engine => "/simple_user", :as => "simple_user"
.gemspec dependencies
s.add_dependency "rails", "~> 3.2.12"
s.add_dependency "devise"
s.add_dependency "cancan"
s.add_dependency "rolify"
s.add_dependency "omniauth"
s.add_dependency "omniauth-facebook", "1.4.1"
s.add_dependency "simple_form"
#s.add_development_dependency "mysql2"
s.add_development_dependency "sqlite3"
s.add_development_dependency "jquery-rails"
s.add_development_dependency "debugger"
Gemfile
source "http://rubygems.org"
gemspec
gem 'devise'
gem 'cancan'
gem 'rolify'
gem 'omniauth'
gem 'omniauth-facebook', '1.4.1'
gem 'simple_form'
# Development
gem 'jquery-rails'
gem 'debugger'
I think the problem is the callback that is not initialised, and the reason may be that OmniAuth doesn't get loaded, but I don't know if it is and how to solve it.
You can check the project in https://github.com/pablomarti/simple_user, and if you want to clone it and test you can use the generator rails g simple_user:install, and you can see the code of test/dummy also to get the idea.
Thank you very much in advance.

Answer 1

The solution was to remove the omniauth.rb and include the middleware of OmniAuth in the engine, so the engine looks like this:
module SimpleUser
require 'rubygems'
require 'devise'
require 'cancan'
require 'rolify'
require 'omniauth'
require 'omniauth-facebook'
require 'simple_form'
class Engine < ::Rails::Engine
isolate_namespace SimpleUser
middleware.use OmniAuth::Builder do
provider :facebook, ENV['FACEBOOK_KEY'], ENV['FACEBOOK_SECRET'], :scope => ENV['FACEBOOK_SCOPE']
end
config.before_configuration do
env_file = File.join(Rails.root, 'config', 'fb_config.yml')
YAML.load(File.open(env_file)).each do |key, value|
ENV[key.to_s] = value.to_s
end if File.exists?(env_file)
env_file = File.join(Rails.root, 'config', 'devise_config.yml')
YAML.load(File.open(env_file)).each do |key, value|
ENV[key.to_s] = value.to_s
end if File.exists?(env_file)
end
end
end
Thanks to Dmitry Lihachev for his answer https://stackoverflow.com/a/8413724/347501 in a similar problem.