ruby-on-rails - rails3 嵌套包括？

Question

是否有正确的写法，或者我的做法有误？我需要做一个嵌套包含。我找到了 This Link但它似乎不起作用。

def show
    @showring = Ring.includes(:stones => :upcharges, :variations).find(params[:id])
end

我有 3 个表... 有很多石头的戒指 has_many upcharges 的石头

模型:

class Ring < ActiveRecord::Base
  has_many :stones
end

class Stone < ActiveRecord::Base
  has_many :upcharges  
  belongs_to :ring  
end

class Upcharge < ActiveRecord::Base
  belongs_to :stone
end

Answer 1

def show
    @showring = Ring.includes([{:stones => :upcharges}, :variations]).find(params[:id])
end

添加了一些括号:)

获取所有附加费:

@showring.stones.each do |s|
  s.upcharges #Do whatever you need with it
end

选项 2:声明一个 has_many :through

class Ring < ActiveRecord::Base
  has_many :stones
  has_many :upcharges, :through => :stones
end

然后在 View 中:

<%= @showring.upcharges.to_json.html_safe %>