auto_loading_file_rule.rb

# Auto loading file rules in Ruby on Rails
# the following class need to be under this file path: app/models/contract/document/uploader.rb
class Contract::Document::Uploader < CarrierWave::Uploader::Base
  ...
end

# This is an issue for us to relocate Mailer::Base(app/mailers/mailer) to app/mailers folder
# I have read online resource I can't find a way to break this. 
# let me know if you find anything, if not, I think we should keep it under app/mailers/mailer for now

# If I need to make this work, I need to define a class without Module name, such as
# mailer_base.rb
class MailerBase
  ...
end

# asked.rb
class Asked < MailerBase
  ...
end

# contact_us.rb
class ContactUs < MailerBase
  ...
end