Entity and Repository

config initializers virtus.rb

EntityVirtus = Virtus.model

ValueObjectVirtus = Virtus.value_object

class UUID < Virtus::Attribute
  class String < ::String
  end

  def coerce(value)
    value.present? ? String.new(value) : nil
  end
end

domain project_domain project project_entity.rb

class ProjectEntity < Entity
  attribute :id, Integer
  attribute :name, String

  set_foreign_keys({
    organization_id: Integer
  })

  set_referenced_attrs({
    test_suites: Array[TestSuiteEntity]
  })
end

domain project_domain test_suite test_suite_entity.rb

class TestSuiteEntity < Entity
  attribute :id, Integer
  attribute :name, String
  attribute :token, String

  set_foreign_keys({
    project_id: Integer
  })
end

domain project_domain test_suite test_suite_repository.rb

class TestSuiteRepository < BaseRepository
  def initialize(entity_class = TestSuiteEntity, model_class = TestSuite)
    super
  end

  def find_by_token(token)
    record = model_class.find_by(token: token)
    return unless record
    entity_class.new(record.attributes)
  end
end

lib ext base_repository.rb

class BaseRepository
  def initialize(entity_class = nil, model_class = nil)
    @entity_class = entity_class
    @model_class = model_class
  end

  def save(entity)
    if entity.id
      record = model_class.find_by(id: entity.id)
      record.update(entity.not_referenced_attrs)
    else
      record = model_class.create(entity.not_referenced_attrs)
    end

    entity_class.new(record.attributes)
  end

  private

  def entity_class
    @entity_class || raise(NotImplementedError)
  end

  def model_class
    @model_class || raise(NotImplementedError)
  end
end

lib ext entity.rb

class Entity
  include EntityVirtus

  class << self
    def set_attrs(attrs={})
      attrs.each do |attr, type|
        attribute attr, type
      end
    end
    alias_method :set_foreign_keys, :set_attrs

    def set_referenced_attrs(attrs={})
      @referenced_attrs = attrs.keys
      set_attrs(attrs)
    end

    def referenced_attrs
      @referenced_attrs || []
    end

    def set_timestamps
      set_attrs({
        updated_at: DateTime,
        created_at: DateTime
      })
    end
  end

  def not_referenced_attrs
    attributes.except(*self.class.referenced_attrs)
  end
end

I don't use repository to initialize new Entity. Entity can be created outside of the repository. I use repository to store Entity in DB. I can ask repository to get entity so the repository handles database query and returns Entity.