Repository pattern example in Ruby for Rails developers

1_brand.rb

module Storage
  module Models
    class Brand < ActiveRecord::Base; end
  end
end

2_brand_entity.rb

module Storage
  module Entities
    class BrandEntity
      include ::Virtus.model

      attribute :id,          String
      attribute :name,        String
      attribute :image,       String
      attribute :description, String
    end
  end
end

3_repository.rb

module Storage
  module Repositories
    module Repository
      def initialize(orm_adapter)
        @orm_adapter = orm_adapter
      end

      def load_all
        orm_adapter.find_each.lazy.map &method(:map_record)
      end

      private
      attr_reader :orm_adapter
    end
  end
end

4_brand_repository.rb

require_relative 'repository'

module Storage
  module Repositories
    class BrandRepository
      include Repository

      def initialize(db = Models::Brand)
        super
      end

      private
      def map_record(record)
        Entities::BrandEntity.new.tap do |brand|
          brand.id          = record.id
          brand.name        = record.name
          brand.image       = record.image
          brand.description = record.description
        end
      end
    end
  end
end

5_query_object.rb

module Storage
  module QueryObjects
    module QueryObject
      def initialize(repository)
        @repository = repository
      end

      private
      attr_reader :repository
    end
  end
end

6_get_all_brand.rb

require_relative 'query_object'

module Storage
  module QueryObjects
    class GetAllBrands
      include QueryObject

      def initialize(repository = Repositories::BrandRepository.new)
        super
      end

      def call
        repository.load_all
      end
    end
  end
end