验证问题的长度

Question

我的问题是：下面的代码工作正常，但有一个特例。如果商品的product_id是1，那么商品最多可以有10个关键字。任何帮助将是appreciated.Thanks

class Item < ActiveRecord::Base 

validates_length_of :keywords, :maximum => 5, :tokenizer => lambda {|str| str.scan(/\w+/) }, :on => :update 

end 

Answer 1

validates_length_of :keywords, :maximum => 5, :tokenizer => lambda {|str| str.scan(/\w+/) }, :on => :update, :unless => lambda { |item| item.product_id == 1 }