Question

Lets say we have a simple model that stores two integers, the min and the max. We would like to force min <= max.

class MinMax
  include MongoMapper::Document

  key :min, Integer
  key :max, Integer

  validate_presence_of :min, :max
end

1) How would you validate that min is indeed equal or less than max?

2) If you don’t think this is the responsibility of the model, then where and who should do that validation?

Answer 1

validates :min_le_max

def min_le_max
  self.min <= self.max
end