Different ways of having modular active record models

concerns.rb

# config/initializers/concerns.rb
class << ActiveRecord::Base
  def concerned_with(*concerns)
    concerns.each do |concern|
      require_dependency "#{name.underscore}/#{concern}"
      klass = concern.to_s.classify.constantize rescue nil
      send(:include, klass) if klass.is_a? Module
    end
  end
end


# Approach #1 opening User class

# app/models/user/validations.rb
class User << ActiveRecord::Base
  validates :mobile, :length => { :in => 6..20 },  :allow_blank => true, :allow_nil => true
  validates_presence_of :country, :name
  before_create :is_zip_validated_by_yahoo?
  # and so on

end

# Approach #2 Let User include module

# app/models/user/module_name.rb
module ModuleName
  def blah_blah_blah
  end # and so on ....

end

# Approach #3 extend ActiveSupport::Concern

# app/models/user/ensure_something_type.rb
module EnsureSomethingType
  extend ActiveSupport::Concern

  included do
    before_create :ensure_something_type

    belongs_to :something_type
    has_one :something_base_type, :through =>  :something_type
  end

  def ensure_something_type
    self.something_type ||= SomethingType.find_by_name("something something")
  end
end


# app/models/user.rb

  concerned_with  :validations,
    :data_uploader,
    :ensure_something_type,
    :jingo_filters,
    :macro_reports,
    :pricing,