Examples on the ways to separate an ActiveRecord domain model from UI layer in Rails/Ruby.

app-service-view-examples.rb

module PropertyManagement
  class OnBoarding
    #
    # **********
    # Setup
    # **********
    #
    # ActiveRecord: None
    # ActiveModel+freeze:  None
    # Hash:         None, but param massaging may be necessary unless everything matches ActiveRecord
    #               which I'm sure in some (many?) cases it shouldn't or wont.
    # Data transfer object:
    #
    class2 :building_object => Building.attribute_names.dup.concat([
      :rentals => Rental.attribute_names
    ])

    # Draper:
    class BuildingObject < Draper::Decorator
      # This will delegate save(), update() etc... which we don't want to do
      # delegate_all

      delegate *Building.attribute_names
      decorates_association :rentals
    end

    #
    # **********
    # Retrieving Records
    # **********
    #
    def buildings(id)
      # ActiveRecord
      Building.find(id)

      # ActiveModel + freeze:
      Building.find(id).freeze

      # Hash
      Building.find(id).as_json(:include_root => false)

      # Data transfer object
      BuildingObject.new(
        Building.find(id).as_json(:include_root => false,
                                  :include => [:rentals])
      )

      # Draper
      Building.find(id).decorate
    end

    def search_buildings(term)
      return [] unless term.present?

      # In all cases Building may be replaced with another class to handle
      # data fetching and/or whatever logic

      # ActiveRecord
      Building.includes(:rentals).where("addr_street like :term or landmark_name like :term", :term => "%#{term}%").limit(10).to_a

      # ActiveModel + freeze:
      Building.includes(:rentals).where("addr_street like :term or landmark_name like :term", :term => "%#{term}%").limit(10).map(&:freeze)

      # Hash
      Building.includes(:rentals).where("addr_street like :term or landmark_name like :term", :term => "%#{term}%").limit(10).map(&:as_json)

      # Data transfer object
      Building.includes(:rentals).where("addr_street like :term or landmark_name like :term", :term => "%#{term}%").limit(10).map do |b|
        BuildingObject.new(b.as_json(:include_root => false, :includes => [:rentals]))
      end

      # Draper:
      # Note: as_json can be called on Draper collections
      Building.includes(:rentals).where("addr_street like :term or landmark_name like :term", :term => "%#{term}%").limit(10).decorate
    end
  end

  #
  # **********
  # Saving Records
  # **********
  #
  # ActiveRecord:
  # company here has not been retrieved from DB. We only do that stuff in here.
  def update_company(company)
    CompanyDS.update(company)
  end

  # ActiveMddel + freeze: Any of these examples

  # Hash:
  def update_company(id, attributes)
    Company.new(attributes) { |c| c.id = id }

    # can also do update(attributes), but attributes may need massaging
    CompanyDS.update(company)
  end

  # Data access object:
  def update_company(company)
    # company here is PORO
    # can also do update(company)
    CompanyDS.update(company.to_h)
  end

  # Draper: Any of the above. Would have to use model or DraperDecorator that accepts model
end

Class2 can be found here: https://github.com/sshaw/class2