有人可以解释这个奇怪的Rails ActiveSupport :: Duration行为吗？

Question

我正在玩游戏时间（和postgres间隔，长篇故事），我得到了这个。

[6] pry(main)> 30.days.days
=> 2592000 days

为什么它不会返回30 days？那不是很有意义吗？我错过了什么......？

Answer 1

You can see the implementation of the days method here and here.

  def days
    AS::Duration.new(self * 24*60*60, [[:days, self]])
  end

So, everytime you call .days it will multiply the current value with 24*60*60 = 86400 and then return the value.

So:

[61] pry(main)> 30.days
=> 30 days
[62] pry(main)> 30.days.days
=> 2592000 days
[63] pry(main)> 30.days.days.days
=> 223948800000 days

So, if you want 30 days, just use 30.days which makes sense!