ActiveAttr stops working on production server - ruby-on-rails

Question

I have created a simple model for handling a contact form:
class ContactForm
include ActiveAttr::Model
attribute :name
attribute :email
attribute :message
attr_accessible :name, :email, :message
validates_presence_of :name, :email, :message
validates_format_of :email, :with => /^[-a-z0-9_+\.]+\#([-a-z0-9]+\.)+[a-z0-9] {2,4}$/i
end
It works fine on the development environment, but gives me an error on the production server, logged in the unicorn log:
E, [2013-01-26T18:15:42.724973 #8940] ERROR -- : uninitialized constant ContactForm::ActiveAttr (NameError)
Gemfile
source 'https://rubygems.org'
gem 'rails', '3.2.11'
# Bundle edge Rails instead:
# gem 'rails', :git => 'git://github.com/rails/rails.git'
gem 'pg'
gem 'bootstrap-sass'
gem 'font-awesome-sass-rails'
# gem 'acts_as_tree', :git => 'git://github.com/amerine/acts_as_tree.git'
gem 'closure_tree'
gem 'kaminari'
gem 'friendly_id'
gem 'slim'
gem 'gmaps4rails'
gem 'devise'
gem 'omniauth'
gem 'oauth2'
gem 'omniauth-facebook'
gem 'omniauth-twitter'
gem 'simple_form'
gem 'pg_search'
gem 'stamp'
gem 'acts-as-taggable-on', '~> 2.3.1'
gem 'rmagick'
gem 'carrierwave'
gem 'active_attr'
gem 'select2-rails'
# gem 'roo'
# Gems used only for assets and not required
# in production environments by default.
group :assets do
gem 'sass-rails', '~> 3.2.3'
gem 'coffee-rails', '~> 3.2.1'
# See https://github.com/sstephenson/execjs#readme for more supported runtimes
# gem 'therubyracer', :platforms => :ruby
gem 'uglifier', '>= 1.0.3'
gem 'compass-rails'
end
group :development do
gem "better_errors"
gem "binding_of_caller"
gem 'guard'
gem 'letter_opener'
end
group :test do
gem 'minitest'
end
gem 'jquery-rails'
# To use ActiveModel has_secure_password
# gem 'bcrypt-ruby', '~> 3.0.0'
# To use Jbuilder templates for JSON
# gem 'jbuilder'
# Use unicorn as the app server
gem 'unicorn'
# Deploy with Capistrano
gem 'capistrano'
# To use debugger
# gem 'debugger'
gem 'bullet', :group => :development
gem 'rack-mini-profiler'

Answer 1

I had the same problem and the fix for me was to specify the version of active_attr in my gemfile.
gem 'active_attr', '0.7.0'
I found an issue on GitHub where someone else had the same problem here.

Answer 2

I have the same problem in development environment.
I followed this step-by-step tutorial https://github.com/thomasklemm/email_form_rails.
When I try to create a new message in console I get :
m=Message.new
NameError: uninitialized constant Message::ActiveAttr
I use Rails 3.2.1, active_attributes gem version is 0.0.1.
EDIT
My fault it seems I made a mistake when installing the gem (not the good one)
change gemfile from
gem 'active_attributes','0.0.1'
to
gem 'active_attr', '0.0.7'
Now it seems to work...