通过ActiveSupport ::关注或自定义验证进行Rails动态模型验证

Question

SO...

I am currently working on a rails project that will result in several models being created with similar fee attributes. What I would like to do is create a re-usable validation mechanism. For example, my model could be..

Foo
  currency
  producer_product_fee
  producer_transport_fee
  consumer_product_fee
  consumer_transport_fee

...and I will have several models of a similar structure (always having two different sides to every fee) and I would like to validate that the fees are non-negative, valid numbers, and that the producer fee is always less than the corresponding consumer fee. Note that the different attributes across models may be named completely different, but it can be assumed that the pair of producer / consumer fees always are named the same, except the prefix. Any tips on how to achieve this would be great.

Answer 1

Something like this perhaps?

validates_numericality_of :producer_product_fee, 
    less_than: Proc.new { |r| r.consumer_product_fee }, 
    greater_than_or_equal_to: 0,
    allow_blank: false