ArgumentError:您需要提供至少一个验证:如果

问题描述

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

看起来一切正常，但是当我在 Rails 控制台中时

All seems ok, but when I in my rails console

irb(main):001:0> Task.new
ArgumentError: You need to supply at least one validation

问题出在哪里?

推荐答案

你忘了告诉 validates 你想如何验证 :deadline.我认为您误解了 :if 的作用；:if =>:deadline_in_future? 选项表示:

You forgot to tell validates how you want to validate :deadline. I think you're misunderstanding what :if does; the :if => :deadline_in_future? option means:

仅当 deadline_in_future? 方法返回真值时才验证 :deadline.

我怀疑您想验证截止日期是在未来:

I suspect that you want to validate that the deadline is in the future:

validate :deadline_in_future?

在Active Record 验证和回调指南中提供了更多详细信息.

Further details are available in the Active Record Validations and Callbacks Guide.

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