ruby-on-rails - Ruby/Rails 继承，在子类中覆盖父类中定义的验证器

Question

我有以下导轨/回形针验证器：

class ImageRatioValidator < ActiveModel::EachValidator
  def validate_each(record, attribute, value)
    attr_name = "#{attribute}_width".to_sym
    value = record.send(:read_attribute_for_validation, attribute)
    valid_ratios = options[:ratio]

    if !value.queued_for_write[:original].blank?
      geo = Paperclip::Geometry.from_file value.queued_for_write[:original]

      # first we need to validate the ratio
      cur_ratio = nil
      valid_ratios.each do |ratio, max_width|
        parts = ratio.split ":"
        next unless (geo.height * parts.first.to_f) == (geo.width * parts.last.to_f)
        cur_ratio = ratio
      end
      # then we need to make sure the maximum width of the ratio is honoured
      if cur_ratio
        if not valid_ratios[cur_ratio].to_f >= geo.width
          record.errors[attribute] << "The maximum width for ratio #{cur_ratio} is #{valid_ratios[cur_ratio]}. Given width was #{geo.width}!"
        end
      else
        record.errors[attribute] << "Please make sure you upload a stall logo with a valid ratio (#{valid_ratios.keys.join(", ")})!"
      end
    end
  end
end

验证器用于超类（超类不是抽象的，因此可以实例化）和子类。在子类中，我需要更改允许的比率：

超类：

class Superclass
    validates_attachment :logo, :image_ratio => { :ratio  => {"1:1" => "28", "4:1" => "50", "5:1" => "40"} }
end

子类：

class Subclass < Superclass
  validates_attachment :logo, :image_ratio => { :ratio  => {"1:1" => "40", "2:1" => "60"} }
end

验证器在超类中按预期工作，但似乎忽略了子类中给出的新比率。
我是否试图以非 Rails 方式使用验证器？在上述情况下，我应该如何使用验证器？

Answer 1

当您从超类继承时，您也可以从中获得验证器。我不是 100% 确定这一点，但我认为您只需将新验证器添加到旧验证器列表中，即两个约束都适用。

我认为最简单的解决方案是将通用逻辑放在模块中或从通用超类继承。你也可以做这样的事情，但我认为这很丑：

class Superclass
    with_options :unless => Proc.new { |a| a.validators.any? } do |super_validators|
        super_validators.validates :password, :length => { :minimum => 10 }
    end
end

Answer 2

这不是理想的解决方案，但相当干净。

只需根据类型使用自定义验证。这样，您将在超类中定义两个验证器，但它肯定会起作用。

class Superclass
    validates_attachment :logo, :image_ratio => { :ratio  => {"1:1" => "28", "4:1" => "50", "5:1" => "40"} }, :if => self.is_a?(SuperClass)
    validates_attachment :logo, :image_ratio => { :ratio  => {"1:1" => "40", "2:1" => "60"} }, :if => self.is_a?(SubClass)
end