问题描述
看，一个 before_filter ：
class ThingController < ApplicationController
before_filter :check_stuff, :if => proc {Rails.env.production?}
end
在最近的代码审查中，我有人问，是否需要 proc 才能正常工作？ 答案似乎是是，但这是一个合理的问题，并且我打算通过参考Rails文档或指南或使用 before_filter （现在为 before_action ）。
During a recent code review, I was asked, "Is 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).
我找不到任何东西。 提到：only / ：除了，但不包括：if / ：除非。
I couldn't find any. The Action Controller Guide mentions :only/:except, but not :if/:unless.
失败了，我可以指出的代码中是否有涵盖此内容的地方？在进行了简短提及。有关如何处理：only 和：except 而不是：if 或：除非。
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.
推荐答案
在Rails上找到它指南：
Found it on Rails Guides: http://guides.rubyonrails.org/active_record_callbacks.html#conditional-callbacks
并非总是需要 Proc 才能工作。
Turns out a Proc isn't always required for it to work.
因此，在您的情况下，您可能会逃脱
So in your case you could probably get away with
before_action :check_stuff, if: "Rails.env.production?"
在Rails文档中查找内容有时会很麻烦，但是至少这样的问题使事情更容易由于StackOverflow索引编制正确且搜索排名较高，因此可以随时查找。
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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