为什么在 Rails 模型类中可以调用回调? [英] Why are callbacks callable in Rails model classes?

问题描述

我有一个像这样的 Rails 模型类:

I have a Rails model class like this:

class Something < ActiveRecord::Base

  before_create do
     self.key = SecureRandom.urlsafe_base64(8)
  end

end

为什么我可以在这里调用 before_create ?我希望它是 ActiveRecord::Base 的一种方法，但它不是.回调是 ActiveRecord::Callbacks 的方法.但是为什么我可以在模型类中调用它们而不包含一些东西?

Why can I call before_create here? I expected it to be a method of ActiveRecord::Base but it is not. Callbacks are methods of ActiveRecord::Callbacks. But why can I call them in a model class without including something?

推荐答案

你可以这样做，因为 ActiveRecord::Base 这样做(或类似的东西，取决于你的 Rails 版本):

You can do that because ActiveRecord::Base does this (or something similar depending on your version of Rails):

Base.class_eval do
  #...
  include Callbacks, ActiveModel::Observing, Timestamp
  #...
end

所以 ActiveRecord::Base 已经包含了 ActiveRecord::Callbacks 并且您的类通过从 ActiveRecord::Base 继承来获取回调.

So ActiveRecord::Base already includes ActiveRecord::Callbacks and your class picks up the callbacks by inheriting from ActiveRecord::Base.

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