Mongoid：has_and_belongs_to_many分配不会触发after_save

Question

我有下一个代码：

def Person
  has_and_belongs_to_many :houses

  def after_save do
    p "After save"
  end
end

def House
  has_and_belongs_to_many :persons
end

p = Person.create
h = House.create
p.house_ids
=> nil

p.houses << h  # it should print 'After save'
p.house_ids
=> ["540591aad9a0d13cee00003e"] 

它应该打印“保存后”，但它不会触发回调，为什么不呢？

Answer 1

因为after_save在创建对象时没有被触发...使用after_create回调并且它会正确打印