I've built a basic Rails app with Mongoid, Devise and Omniauth for Facebook login. I've got no problem running it locally, but when I try to push to Heroku, I'm getting this error:

"/app/app/controllers/Users/omniauth_callbacks_controller.rb:1:in `': uninitialized     constant Users (NameError)"

I've Googled the hell out of this with little luck. I've committed the User model, I've ran "heroku run rake db:migrate", etc. No luck. Here's my stack.

Ruby 1.9.2
Rails 3.2.1

Gemfile:

require 'rbconfig'
HOST_OS = RbConfig::CONFIG['host_os']
source 'https://rubygems.org'
gem 'rails', '3.2.1'
group :assets do
gem 'sass-rails',   '~> 3.2.3'
gem 'coffee-rails', '~> 3.2.1'
gem 'uglifier', '>= 1.0.3'
end
gem 'jquery-rails'

gem "bson_ext", ">= 1.6.1"
gem "mongoid"
gem "devise"
gem "zurb-foundation"
gem "omniauth"
gem 'omniauth-facebook'
gem 'gravatar_image_tag'

Gemfile.lock:

GEM
remote: https://rubygems.org/
specs:
actionmailer (3.2.1)
  actionpack (= 3.2.1)
  mail (~> 2.4.0)
actionpack (3.2.1)
  activemodel (= 3.2.1)
  activesupport (= 3.2.1)
  builder (~> 3.0.0)
  erubis (~> 2.7.0)
  journey (~> 1.0.1)
  rack (~> 1.4.0)
  rack-cache (~> 1.1)
  rack-test (~> 0.6.1)
  sprockets (~> 2.1.2)
activemodel (3.2.1)
  activesupport (= 3.2.1)
  builder (~> 3.0.0)
activerecord (3.2.1)
  activemodel (= 3.2.1)
  activesupport (= 3.2.1)
  arel (~> 3.0.0)
  tzinfo (~> 0.3.29)
activeresource (3.2.1)
  activemodel (= 3.2.1)
  activesupport (= 3.2.1)
activesupport (3.2.1)
  i18n (~> 0.6)
  multi_json (~> 1.0)
addressable (2.2.7)
arel (3.0.2)
bcrypt-ruby (3.0.1)
bson (1.6.1)
bson_ext (1.6.1)
  bson (~> 1.6.1)
builder (3.0.0)
coffee-rails (3.2.2)
  coffee-script (>= 2.2.0)
  railties (~> 3.2.0)
coffee-script (2.2.0)
  coffee-script-source
  execjs
coffee-script-source (1.2.0)
devise (2.0.4)
  bcrypt-ruby (~> 3.0)
  orm_adapter (~> 0.0.3)
  railties (~> 3.1)
  warden (~> 1.1.1)
erubis (2.7.0)
execjs (1.3.0)
  multi_json (~> 1.0)
faraday (0.7.6)
  addressable (~> 2.2)
  multipart-post (~> 1.1)
  rack (~> 1.1)
gravatar_image_tag (1.0.0)
hashie (1.2.0)
hike (1.2.1)
i18n (0.6.0)
journey (1.0.3)
jquery-rails (2.0.2)
  railties (>= 3.2.0, < 5.0)
  thor (~> 0.14)
json (1.6.6)
mail (2.4.4)
  i18n (>= 0.4.0)
  mime-types (~> 1.16)
  treetop (~> 1.4.8)
mime-types (1.18)
mongo (1.6.1)
  bson (~> 1.6.1)
mongoid (2.4.7)
  activemodel (~> 3.1)
  mongo (~> 1.3)
  tzinfo (~> 0.3.22)
multi_json (1.2.0)
multipart-post (1.1.5)
oauth2 (0.5.2)
  faraday (~> 0.7)
  multi_json (~> 1.0)
omniauth (1.0.3)
  hashie (~> 1.2)
  rack
omniauth-facebook (1.2.0)
  omniauth-oauth2 (~> 1.0.0)
omniauth-oauth2 (1.0.0)
  oauth2 (~> 0.5.0)
  omniauth (~> 1.0)
orm_adapter (0.0.7)
polyglot (0.3.3)
rack (1.4.1)
rack-cache (1.2)
  rack (>= 0.4)
rack-ssl (1.3.2)
  rack
rack-test (0.6.1)
  rack (>= 1.0)
rails (3.2.1)
  actionmailer (= 3.2.1)
  actionpack (= 3.2.1)
  activerecord (= 3.2.1)
  activeresource (= 3.2.1)
  activesupport (= 3.2.1)
  bundler (~> 1.0)
  railties (= 3.2.1)
railties (3.2.1)
  actionpack (= 3.2.1)
  activesupport (= 3.2.1)
  rack-ssl (~> 1.3.2)
  rake (>= 0.8.7)
  rdoc (~> 3.4)
  thor (~> 0.14.6)
rake (0.9.2.2)
rdoc (3.12)
  json (~> 1.4)
sass (3.1.15)
sass-rails (3.2.5)
  railties (~> 3.2.0)
  sass (>= 3.1.10)
  tilt (~> 1.3)
sprockets (2.1.2)
  hike (~> 1.2)
  rack (~> 1.0)
  tilt (~> 1.1, != 1.3.0)
thor (0.14.6)
tilt (1.3.3)
treetop (1.4.10)
  polyglot
  polyglot (>= 0.3.1)
tzinfo (0.3.32)
uglifier (1.2.4)
  execjs (>= 0.3.0)
  multi_json (>= 1.0.2)
warden (1.1.1)
  rack (>= 1.0)
zurb-foundation (2.2.0.2)
  jquery-rails (>= 1.0)
  rails (~> 3.1)

PLATFORMS
ruby

DEPENDENCIES
 bson_ext (>= 1.6.1)
 coffee-rails (~> 3.2.1)
 devise
 gravatar_image_tag
 jquery-rails
 mongoid
 omniauth
 omniauth-facebook
 rails (= 3.2.1)
 sass-rails (~> 3.2.3)
 uglifier (>= 1.0.3)
 zurb-foundation

Controller:

class Users::OmniauthCallbacksController < Devise::OmniauthCallbacksController
  def facebook
  # You need to implement the method below in your model
@user = User.find_for_facebook_oauth(request.env["omniauth.auth"], current_user)

if @user.persisted?
  flash[:notice] = I18n.t "devise.omniauth_callbacks.success", :kind => "Facebook"
  sign_in_and_redirect @user, :event => :authentication
else
  session["devise.facebook_data"] = request.env["omniauth.auth"]
  redirect_to new_user_registration_url
end
end
end

Any thoughts ?

• ruby-on-rails-3
• heroku
• devise
• omniauth

I had this issue; I know it's a late answer but I wanted to add this for whoever needed it.

Make sure that your OmniauthCallbacksController IS IN A users FOLDER. "app/controllers/users/omniauth_callbacks_controller.rb"

Unlikely, but if you used "rails generate scaffold", or "rails generate controller" to create the controller, you need to "git add -A" to add all the newly created files to your repository. (1) git add -A (2) git commit -m "new files added" (3) git push [assuming you're also using a remote repo] (4) git push heroku master (5) heroku run rake db:migrate

This would be a "Rookie Mistake", but would explain the error above. Don't ask how I know!

Just thought I'd add that I had this issue and that the above solutions didn't work for me. It turns out the cause in my case was that Devise had capitalized the Users subfolder's name (/app/app/controllers/Users). Deleting the folder from git and then readding it with the proper lowercase name of "users" (/app/app/controllers/users) solved my issue.