验证是否包含在选项数组中或为零 [英] Validate on inclusion within array of options OR be nil

问题描述

我有一个模型，希望将字段的输入限制为nil或落在指定值数组之内。我可以使包含部分起作用，但是 allow_nil：true 的位对我似乎不起作用：

I have a model where I'd like to restrict input for a field to either be nil or fall within a specified array of values. I can get the inclusion part working, but the allow_nil: true bit doesn't seem to work for me:

class Mock::Patient < ActiveRecord::Base
  LANGUAGE_OPTIONS = %w[English Spanish French German Chinese Hindi Punjabi]
  validates :preferred_language, inclusion: { in: LANGUAGE_OPTIONS }
end

我尝试将最后一行修改为：

I've tried modifying that last line to things like:

  validates :preferred_language, inclusion: { in: LANGUAGE_OPTIONS }, allow_nil: true

但无济于事。表达这种简单包含或nil组合的最简单方法是什么？

But to no avail. What's the simplest way to express this combination of simple inclusion or nil?

推荐答案

允许nil进行验证而又仍然允许的正确格式有限的值数组如下：

the correct form to allow nil to validate while still allowing a limited array of values is the following:

validates :preferred_language, inclusion: { in: LANGUAGE_OPTIONS, allow_nil: true }

注意allow_nil选项是如何在内部包含选项哈希

notice how the allow_nil option is inside the inclusion option hash

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