model_version_observer.rb

class ModelVersionObserver < ActiveRecord::Observer
  observe MyReferenceDataModel

  [:create, :update, :destroy].each do |action|
    define_method("after_#{action}") do |record|
      increment_model_version_of_observed(record, action)
    end
  end

  private

  def increment_model_version_of_observed(record, action)
    unless record.skip_observation_on.include?(action)
      model_version = ModelVersion.find_by_model_name(model_name = record.class.name)
      if model_version
        model_version.increment_version!
      else
        ModelVersion.create!(:model_name => model_name)
      end
    end
  end
end