ruby-on-rails - rails 3 : How to validate that A < B where A and B are both model attributes?

Question

我想验证 customer_price >= my_price .我尝试了以下方法:

class Product < ActiveRecord::Base
  attr_accessor :my_price
  validates_numericality_of :customer_price, :greater_than_or_equal_to => my_price
  ...
end

( customer_price 是数据库中 Products 表中的一列，而 my_price 不是。)

结果如下:

NameError in ProductsController#index
undefined local variable or method `my_price' for #<Class:0x313b648>

在 Rails 3 中执行此操作的正确方法是什么？

Answer 1

创建自定义验证器:

validate :price_is_less_than_total

# other model methods

private

  def price_is_less_than_total
    errors.add(:price, "should be less than total") if price > total
  end