インピーダンスを解決したいの会

product_mapper.rb

class ProductMapper
  def attributes
    [:id, :name, :price]
  end
  
  def self.map(relation, limit: nil)
    mapping_type = Struct.new(attributes)
    relation.limit(limit).pluck(attributes).map do |record|
      mapping_type.new(record)
    end
  end
end

products_controller.rb

class ProductsController < ApplicationController
   def index
     rel = Product.available
     @products = ProductMapper.map(rel, limit: 30)
   end
end