after_initialize& after_find回调顺序在Active Record对象生命周期中？ [英] after_initialize & after_find callbacks order in Active Record object life cycle?

问题描述

来自Rails指南。回调可能会涉及Active Record Object的生命周期。按照执行顺序（从Rails Guides复制）：

From the Rails Guides. Callbacks could hook into Active Record Object's life cycle. In the order of execution, they're (copied from Rails Guides):

• before_validation


• after_validation


• before_save


• around_save


• before_create


• around_create


• after_create


• after_save


• after_commit / after_rollback

• before_validation
• after_validation
• before_save
• around_save
• before_create
• around_create
• after_create
• after_save
• after_commit/after_rollback

• 验证前


• after_validation


• before_save


• around_save


• before_update


• around_update


• 更新后


• after_save


• after_commit / after_rollback

• before_validation
• after_validation
• before_save
• around_save
• before_update
• around_update
• after_update
• after_save
• after_commit/after_rollback

• before_destroy


• around_destroy


• after_destroy


• after_commit / after_rollback

• before_destroy
• around_destroy
• after_destroy
• after_commit/after_rollback

我想知道将 after_initialize放在哪里和 after_find 到上面？我认为 after_initialize 应该放在 before_validation 之前，而 after_find 不应该放在属于其中任何三个。我对么？谢谢。

I am wondering where to put the after_initialize and after_find into above? I think after_initialize should put before before_validation and after_find does not belongs to any three of them. Am I correct? Thanks.

推荐答案

after_initialize 和 after_find 回调是两个特殊的回调。

The after_initialize and after_find callbacks are the two special callbacks.

为 after_find 和 after_initialize 事件将它们定义为方法。如果您尝试将它们声明为处理程序，它们将被忽略。

The only way to define callbacks for the after_find and after_initialize events is to define them as methods. If you try declaring them as handlers,they’ll be silently ignored.

来自 API

对象，都会触发> after_find 和 after_initialize 回调。
after_initialize 在实例化新对象后也会触发
。

after_find and after_initialize callback is triggered for each object that is found and instantiated by a finder, with after_initialize being triggered after new objects are instantiated as well.

来自指南

每当实例化
Record对象时，都会调用 after_initialize 回调，直接使用new或从数据库加载
记录时。避免需要
直接覆盖您的Active Record初始化方法很有用。

The after_initialize callback will be called whenever an Active Record object is instantiated, either by directly using new or when a record is loaded from the database. It can be useful to avoid the need to directly override your Active Record initialize method.

after_find 每当Active Record从数据库加载
a记录时，都会调用回调。如果同时定义了 after_find ，则在
之前调用 after_initialize 。

The after_find callback will be called whenever Active Record loads a record from the database. after_find is called before after_initialize if both are defined.

after_initialize 和 after_find 回调没有 before_ *
对应对象，但可以像其他活动
Record回调一样注册它们。

The after_initialize and after_find callbacks have no before_* counterparts, but they can be registered just like the other Active Record callbacks.

class User < ActiveRecord::Base
  after_initialize do |user|
    puts "You have initialized an object!"
  end

  after_find do |user|
    puts "You have found an object!"
  end
end

>> User.new
You have initialized an object!
=> #<User id: nil>

>> User.first
You have found an object!
You have initialized an object!
=> #<User id: 1>

在何处放置<$ c是在AR对象生命周期中使用$ c> after_initialize 和 after_find ？

由于它们与所有其他回调不同，并且它们没有 before_ *对应对象，因此作者（指指南此处的作者）可能有兴趣将它们分开，因为它们是特例。

Since they are different from all other callbacks and also they don't have before_* counterparts,so the author(referring to Guides author here) might be interested in putting them separately as they are special case.

最后，我同意将 after_initialize 放在 before_validation 之前。可能是这样。

And finally I would agree with in putting after_initialize before before_validation. It might be the case.

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