有条件的before_action / before_filter的文档 [英] Documentation for conditional before_action/before_filter

问题描述

ApplicationController
before_filter：check_stuff，：if => proc {Rails.env.production？}
end

在最近的代码审查期间，我被问及是否需要 proc 。答案似乎是是，但这是一个合理的问题，我打算通过参考Rails文档或指南或使用条件符号与 before_filter （现在是 before_action 的别名）。

我找不到任何内容。有没有描述这种用法的（当前和官方）指南或文档？ 操作控制台指南提到：仅 / ：除了，但不是：如果 / ：除非。

没有这个，代码中有什么地方可以指出这一点吗？简要介绍这里，但这更多关于如何：只有和：除了，而不是：if 或：除非。

解决方案

在Rails指南中找到： http://guides.rubyonrails.org/active_record_callbacks.html#conditional-callbacks

发现一个 Proc 并不总是需要它工作。

：if 和：除非选项，可以采取符号，一个字符串，一个 Proc 或 Array 。

所以在你的情况下，你可能会摆脱

  before_action：check_stuff，if： Rails.env.production？ 
  

有时在Rails文档中查找内容可能会很痛苦，但至少这样的问题会使事情变得更容易随着时间的推移，StackOverflow被很好地编入索引并具有很高的搜索排名。

Behold, a before_filter:

class ThingController < ApplicationController
  before_filter :check_stuff, :if => proc {Rails.env.production?}
end

During a recent code review, I was asked whether the proc is required for this to work. The answer appears to be 'yes', but it's a reasonable question, and I had intended to answer it by referring to the Rails docs or guides or something on the use of conditionals with before_filter (now an alias of before_action).

I couldn't find any. Is there a (current and official) guide or documentation that describes this usage? The Action Controller Guide mentions :only/:except, but not :if/:unless.

Failing that, is there somewhere in the code I can point to that covers this? It's mentioned briefly here, but that's more about how :only and :except are handled, rather than :if or :unless.

解决方案

Found it on Rails Guides: http://guides.rubyonrails.org/active_record_callbacks.html#conditional-callbacks

Turns out a Proc isn't always required for it to work.

the :if and :unless options, which can take a symbol, a string, a Proc or an Array.

So in your case you could probably get away with

before_action :check_stuff, if: "Rails.env.production?"

Finding things in Rails documentation can be a pain sometimes, but at least questions like this make things easier to find over time since StackOverflow is well indexed and has high search rankings.

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