问号和冒号-如果还有红宝石 [英] question mark and colon - if else in ruby

问题描述

我有一个关于轨道上的红宝石的问题

Hi I have a question about ruby on rails

显然我有这样的声明：

def sort_column
    Product.column_names.include?(params[:sort]) ? params[:sort] : "name"
end

从我的读物来看该方法基于params [：sort]对列进行排序，如果没有params，则产品将按名称进行排序。但是，我不理解该语句的编写方式，尤其是第二个？。有人可以向我解释吗？

From what I read, it's said that this method sort the column based on params[:sort] and if there no params the products will be sorted by "name". However, I don't understand the way this statement is written, especially the second "?". Can someone explain it to me ?

推荐答案

这是您的代码，已重新排列以便于理解。

This is your code, rearranged for easier understanding.

def sort_column
  cond = Product.column_names.include?(params[:sort]) 
  cond ? params[:sort] : "name"
  #  it's equivalent to this
  # if cond
  #   params[:sort]
  # else
  #   'name'
  # end
end

第一个问号是方法名称的一部分，第二个-三元运算符的一部分（您应该了解一下）。

First question mark is part of a method name, the second one - part of ternary operator (which you should read about).

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