如何根据特定范围验证模型的日期属性（在运行时评估） [英] How to validate a model's date attribute against a specific range (evaluated at run time)

问题描述

我有几个具有日期属性的模型，每个模型我想根据给定的范围验证这些日期。一个基本的例子是：

I have several models with a date attribute and for each model I'd like to validate these dates against a given range. A basic example would be:

validates_inclusion_of  :dated_on, :in => Date.new(2000,1,1)..Date(2020,1,1)

理想情况我想在运行时评估日期范围，使用类似于 named_scope 使用的方法，例如：

Ideally I'd like to evaluate the date range at runtime, using a similar approach as named_scope uses, e.g:

validates_inclusion_of  :dated_on, :in => lambda {{ (Date.today - 2.years)..(Date.today + 2.years)}}

$ b $当然，上述方法不行，那么实现相同结果的最好办法是什么呢？

The above doesn't work of course, so what is the best way of achieving the same result?

推荐答案

如果每个类的验证相同，答案相当简单：将验证方法放在模块中并混合在每个模型中，然后使用验证来添加验证：

If the validation is the same for each class, the answer is fairly simple: put a validation method in a module and mix it in to each model, then use validate to add the validation:

# in lib/validates_dated_on_around_now
module ValidatesDatedOnAroundNow
  protected

  def validate_dated_around_now
    # make sure dated_on isn't more than five years in the past or future
    self.errors.add(:dated_on, "is not valid") unless ((5.years.ago)..(5.years.from_now)).include?(self.dated_on)
  end
end

class FirstModel
  include ValidatesDatedOnAroundNow
  validate :validate_dated_around_now
end

class SecondModel
  include ValidatesDatedOnAroundNow
  validate :validate_dated_around_now
end

如果你想要每个模型的不同范围，你可能想要更像这样的东西：

If you want different ranges for each model, you probably want something more like this:

module ValidatesDateOnWithin
  def validates_dated_on_within(&range_lambda)
    validates_each :dated_on do |record, attr, value|
      range = range_lambda.call
      record.errors.add(attr_name, :inclusion, :value => value) unless range.include?(value)
    end
  end
end

class FirstModel
  extend ValidatesDatedOnWithin
  validates_dated_on_within { ((5.years.ago)..(5.years.from_now)) }
end

class SecondModel
  extend ValidatesDatedOnWithin
  validates_dated_on_within { ((2.years.ago)..(2.years.from_now)) }
end

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