Ruby-on-rails ArgumentError：您需要提供至少一个验证：如果
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ArgumentError: You need to supply at least one validation with :if
提问by Ximik
I have a simple model
我有一个简单的模型
class Task < ActiveRecord::Base
validates :deadline, :if => :deadline_in_future?
def deadline_in_future?
Date.today < self.deadline
end
end
All seems ok, but when I in my rails console
一切看起来都很好，但是当我在我的 Rails 控制台中时
irb(main):001:0> Task.new
ArgumentError: You need to supply at least one validation
Where is the problem?
问题出在哪儿？
回答by zarne
You must change validatesto validate.
您必须更改validates为validate。
回答by mu is too short
You forgot to tell validateshow you want to validate :deadline. I think you're misunderstanding what :ifdoes; the :if => :deadline_in_future?option means:
你忘了告诉validates你想如何验证:deadline。我认为你误解了什么:if；该:if => :deadline_in_future?选项意味着：
Validate
:deadlineonly if thedeadline_in_future?method returns a true value.
:deadline仅当该deadline_in_future?方法返回真值时才进行验证。
I suspect that you want to validate that the deadline is in the future:
我怀疑您想验证截止日期是在未来：
validate :deadline_in_future?
Further details are available in the Active Record Validations and Callbacks Guide.
回答by KL-7
It says you do not pass any validations to validatesmethod. Like validates :presence, for example. What are you trying to validate?
它说你没有通过任何验证validates方法。像validates :presence，例如。你想验证什么？
