Ruby on Rails 2.1 - 回调函数

在活动记录对象的生命周期中，您可以挂接八个事件 −

• (-) save
• (-) valid?
• before_validation
• before_validation_on_create
• (-) verify
• (-) verify_on_create
• after_validation
• after_validation_on_create
• before_save
• before_create
• (-) create
• after_create
• after_save
• before_create
• (-) create
• after_create
• after_save

示例

class Subscription < ActiveRecord::Base
   before_create :record_signup
	
   private
   def record_signup
      self.signed_up_on = Date.today
   end
end

class Firm < ActiveRecord::Base
   # Destroys the associated clients and 
   # people when the firm is destroyed
   before_destroy{
      |record|Person.destroy_all "firm_id= #{record.id}"
   }
   before_destroy{
      |record|Client.destroy_all "client_of= #{record.id}"
   }
end

rails-quick-guide.html