ruby-on-rails - counter_cache 用于多级关联

Question

我有 3 个模型:Topic , Post , Link .

class Topic < ActiveRecord::Base
  has_many :posts
end

class Post < ActiveRecord::Base
  has_many :links
  belongs_to :topic
end

class Link < ActiveRecord::Base
  belongs_to :post
end

我想要 counter_cache论坛 Link模型。
我怎样才能做到这一点 ？

Answer 1

查看 counter_culture gem .

来自 readme :

class Product < ActiveRecord::Base
  belongs_to :sub_category
  counter_culture [:sub_category, :category]
end

class SubCategory < ActiveRecord::Base
  has_many :products
  belongs_to :category
end

class Category < ActiveRecord::Base
  has_many :sub_categories
end

在上面的例子中， Category模型将在 products_count 中保持最新的计数器缓存。 categories table 的列.