Ruby：IF语句中的Nils [英] Ruby: Nils in an IF statement

问题描述

  if params.present？ 
 if params [：search] .present？ 
 if params [：search] [：tags_name_in] .present？ 
 ... 
 end 
 end 
 end 
  

我想问的是params [：search] [：tags_name_in]是否已被定义，但是因为params和params [：search]和params [：search] [：tags_name_in]可能全部为零，如果我使用...

  if params [：search] [：tags_name_in] .present？ 
  

...如果没有参数或没有搜索参数，我得到一个错误。

当然必须有更好的方法来做到这一点......建议

解决方案

<如果你只是想看看它的定义为什么不保持简单并使用定义？函数？

  if defined？（params [：search] [：tags_name_in]）
  

I have the following very ugly ruby code in a rails app I'm working on:

if params.present?
  if params[:search].present?
    if params[:search][:tags_name_in].present?
      ...
    end
  end
end

All I'm trying to ask is whether params[:search][:tags_name_in] has been defined, but because params, and params[:search], and params[:search][:tags_name_in] might all be nil, if I use...

if params[:search][:tags_name_in].present?

... I get an error if there are no params or no search params.

Surely there must be a better way to do this... suggestions??

解决方案

if you are just trying to see if its defined why not keep it simple and use the defined? function?

if defined?(params[:search][:tags_name_in])

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