Rails - 如何仅在另一个字段具有特定值时验证字段? [英] Rails - How to validate a field only if a another field has a certain value?

问题描述

我对 Rails 还很陌生，现在遇到了一个问题，我的朋友 Google 无法解决这个问题:)

I'm pretty new to Rails and I now came across a problem which I wasn't able to solve with my friend Google :)

在我的表单中，我有一个包含三个值的 Select:Apple、Banana 和 Cherry.如果我选择苹果，我隐藏了一个带有一些javascript的另一个选择 - 和一个文本字段，因为选择苹果时，无需填写这些其他两个字段了.

In my form I have a Select with three values: Apple, Banana and Cherry. If I choose Apple from the select I hide another Select- and a Text-field with some Javascript, because when Apple is chosen, there is no need to fill in these other two fields anymore.

所以现在我在提交表单时验证表单有问题.我发现了一些类似的问题，例如只有在另一个字段为空时才验证一个字段."

So now I have a problem with validating my form when it's submitted. I've found some similar problems for example in the case of "Only validate a field if another is blank."

这个问题是这样解决的:

This Problem was solved like this:

validates_presence_of :mobile_number, :unless => :home_phone?

所以我刚刚尝试了我想到的第一件事:

So I've just tried the first thing which popped into my mind:

validates_presence_of :state, :granted_at, :if => :type != 1

但是当我运行它时，我得到这个错误:

But when I run it, I get this error:

undefined method `validate' for true:TrueClass

所以现在我没有找到如何从创建的对象中访问值...提前感谢您的帮助，我希望我的问题不像听起来那么明显:-)

So now I didn't find out how I can access values from the object which was created... Thank you in Advance for your help and I hope my question isn't as obvious as it sounds :-)

推荐答案

因为它是可执行代码，所以您需要将其包装在 lambda 或 Proc 对象中，如下所示:

Because it is executable code you need to wrap it in a lambda or a Proc object like so:

validates_presence_of :state, :granted_at, :if => lambda { |o| o.type != 1 }

# alternatively:
..., :if => lambda { self.type != 1 }
..., :if => Proc.new { |o| o.type != 1 }
..., :if ->(o) { o.type != 1 }

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