ruby-on-rails - 为什么使用 before_action 没有双重渲染？

Question

我想知道为什么在 before_action 中有 redirect_to 或 render 时没有双重渲染。考虑这个例子:

class SomeController < ApplicationController
 before_action :callback

 def new
  callback2
  render 'new'
 end

 def callback
  render 'new'
 end

 def callback2
  render 'new'
 end

end

我看到 before_action 如果不能重定向就没用了，但它是如何制作的？如果我评论 before_action 它会抛出异常。before_action 是如何实现的而不导致双重渲染？

Answer 1

参见 Rails Guide on controllers :

If a "before" filter renders or redirects, the action will not run. If there are additional filters scheduled to run after that filter, they are also cancelled.