npc_loader.rb

require 'clerk'
require 'csv' 

class ClassIdTransformer
  def self.transform(id)
    case id.to_i
    when 1
      "Fighter"
    when 2
      "Mage"
    when 3
      "Cleric"
    else
      "Guard"
    end
  end  
end

class NPCLoader < Clerk::Base
  template do |t|
    t.ignored
    t.named :name
    t.named :race
    t.named :gender
    t.named :class
    t.ignored
    t.grouped(:loot) do |g|
      g.named :name
      g.named :quantity
    end
  end

  validates_presence_of :name, :race, :class

  transforms :'loot/quantity' do |qty|
    qty.to_i
  end

  transforms_with ClassIdTransformer, :class
end

npc_csv_data = <<-END_NPC
1,Fhaemita Dewshining,Half-elf,Female,3,80
2,Ravastine Soulaxe,Dwarf,Female,3,90,Mirthil Axe,1,Gold,2,Silver,21
3,Otifire Smilebeard,Gnome,Male,2,70,Silk Robe,1,Emerald,1,Tapers,10,Spellbook,1
4,Xyrsys Taletreader,Dwarf,Female,6,85,Old Stick,1
END_NPC

npcs = CSV.parse npc_csv_data
loader = NPCLoader.new
loader.load npcs

loader.results

=> [{:name=>"Fhaemita Dewshining",
  :race=>"Half-elf",
  :gender=>"Female",
  :class=>"Cleric",
  :loot=>[]},
 {:name=>"Ravastine Soulaxe",
  :race=>"Dwarf",
  :gender=>"Female",
  :class=>"Fighter",
  :loot=>
   [{:name=>"Mirthil Axe", :quantity=>1},
    {:name=>"Gold", :quantity=>2},
    {:name=>"Silver", :quantity=>21}]},
 {:name=>"Otifire Smilebeard",
  :race=>"Gnome",
  :gender=>"Male",
  :class=>"Mage",
  :loot=>
   [{:name=>"Silk Robe", :quantity=>1},
    {:name=>"Emerald", :quantity=>1},
    {:name=>"Tapers", :quantity=>10},
    {:name=>"Spellbook", :quantity=>1}]},
 {:name=>"Xyrsys Taletreader",
  :race=>"Dwarf",
  :gender=>"Female",
  :class=>"Guard",
  :loot=>[{:name=>"Old Stick", :quantity=>1}]}]