Rails:验证字符串的最小和最大长度，但将其留空 [英] Rails: Validating min and max length of a string but allowing it to be blank

问题描述

我有一个要验证的字段.我希望该字段可以保留为空白，但是如果用户正在输入数据，我希望它采用某种格式.当前，我在模型中使用以下验证，但这不允许用户将其留空:

validates_length_of :foo, :maximum => 5
validates_length_of :foo, :minimum => 5

我该如何写这篇文章来实现自己的目标?

解决方案

我认为可能需要这样的东西:

validates_length_of :foo, minimum: 5, maximum: 5, allow_blank: true

更多示例: ActiveRecord :: Validations :: ClassMethods

I have a field that I would like to validate. I want the field to be able to be left blank, but if a user is entering data I want it to be in a certain format. Currently I am using the below validations in the model, but this doesn't allow the user to leave it blank:

validates_length_of :foo, :maximum => 5
validates_length_of :foo, :minimum => 5

How do I write this to accomplish my goal?

解决方案

I think it might need something like:

validates_length_of :foo, minimum: 5, maximum: 5, allow_blank: true

More examples: ActiveRecord::Validations::ClassMethods

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