Mongoid：has_and_belongs_to_many幽会不会触发after_save的

Question

我有下面的代码：

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"] 

它应打印“保存后”，但它不会触发回调，为什么不呢？

Answer 1

因为after_save不会被触发创建对象时，...利用after_create回调，它会正确打印