如何在Model类中访问类变量

做这个:

class Order < ActiveRecord::Base
   cattr_reader :test, :threshold
   self.test = 123
   self.threshold = {
     VIP: 500,
     PLATINUM: 20000
   }
end  

Order.test

或者我使用常量:

class Order < ActiveRecord::Base
   TEST = 123
end

Order::TEST