ruby-on-rails - rails : How to implement counter caching with self-referential Many to Many via has_many :through

Question

如何为使用 has_many :through 的自引用多对多关系滚动我自己的计数器缓存?

我需要跟踪每篇文章的引用次数和引用文献数量

我大致使用了这个答案中的代码 question :

class Publication < ActiveRecord::Base
  has_many :citations
  has_many :cited_publications, :through => :citations, :source => :reference
  has_many :references, :foreign_key => "reference_id", :class_name => "Citation"
  has_many :refered_publications, :through => :references, :source => :publication
end

class Citation < ActiveRecord::Base
  belongs_to :publication
  belongs_to :reference, :class_name => "Publication"
end

Answer 1

Rails 计数器缓存机制使用 increment_counter和 decrement_counter内部方法。您应该能够从 standard ActiveRecord callbacks 调用这些方法。 .

这样的事情应该给你的想法:

class Citation < ActiveRecord::Base
  belongs_to :publication
  belongs_to :reference, :class_name => "Publication"

  after_create  :increment_counter_cache
  after_destroy :decrement_counter_cache

  private
  def decrement_counter_cache
    Publication.decrement_counter("citations_counter", publication_id)
  end

  def increment_counter_cache
    Publication.increment_counter("citations_counter", publication_id)
  end

结尾