Ruby on rails克隆/重複與篩選嵌套元素

Question

我有一個問題，試圖克隆具有嵌套元素的對象。我知道如何完全克隆它，但我想克隆每個嵌套級別上的一些子元素。

所以可以說我有結構像這樣，通過實例名稱即時決策（它不是實際情況）

class Town < ActiveRecord::Base 
has_many :districts 
has_many :buildings, through: :districts 

class District < ActiveRecord::Base 
belongs_to :town 
has_many :buildings 

class Building < ActiveRecord::Base 
belongs_to :district 
has_many :rooms 
has_many :toilets 

#and i have of course rooms and toilets with belongs_to relation to Building 

所以basicaly，如果我想克隆整個現有城區對象我只想做一些像

Town.last.clone 

但我想這樣做，而不是。我想複製現有的城鎮，然後根據我的收藏重新創建僅一些兒童物品。因此，如果城鎮有10個地區，我想只複製其中的一個，或者更多（基於我的收藏），然後地區有100個房屋，我將再次僅複製我需要的房間，直到房間和洗手間。所以我嘗試了這樣的事情。

#now i have these collections, i get them in some fashion, and they belong to Town(1) below  
districts = District.find(1,2,3) #those ids are belonging to Town 
buildings = Building.find(1,2,3) #those ids are belonging to districts above 
rooms = Room.find(1,2,3,4,5,6) # and are belonging to some of buildings above 
toilets = Toilet.find(1,2,3,4,5,6,7) #and are belonging to some of buildings 

#so now i want to do this 
old_town = Town.find(1) 
new_town = old_town.dup.tap 

districts.each od |district| 
    new_town.districts << district.dup 
end 
#and i get all the districts to new created town but when i try further in nesting it wont work, like this 

districts.each od |district| 
    new_town.districts << district.dup 

    buildings.each do |building| 
    district.buildings << building.dup 
    end 
end 

#and so on inside it for toilets and rooms it just wont work, like it doesnt attach them to new_town. What am i doing wrong? 

所以我只是想選擇性的dup /克隆過濾元素屬於父母。彼此尊重他們的關係。

謝謝分配。

Answer 1

districts.each do |district| 
    district_dup = district.dup 
    buildings.each do |building| 
    district_dup.buildings << building.dup 
    end 
    new_town.districts << district_dup 
end 

你可以試試類似的東西嗎？如果您想添加房間和廁所，則需要創建building_dup，就像district_dup一樣。

編輯：清潔版本

districts.map(&:dup).each do |dis| #creates an Array of duplications and iterates through elements 
    dis.buildings = buildings.map(&:dup).each do |building| #creates an Array of duplications which is later added to dis.buildings 
    building.rooms = rooms.map(&:dup) 
    building.toilets = toilet.map(&:dup) 
    end 
end 

如果dis.buildings = buildings.map(&:dup).each失敗，請嘗試在所有的情況下改變#=到#concat。