app/validators/width_validator.rb

   1 # frozen_string_literal: true
   2
   3 class WidthValidator < ActiveModel::Validations::LengthValidator
   4   module WidthAsLength
   5     def length
   6       Unicode::DisplayWidth.of(to_s)
   7     end
   8   end
   9
  10   def validate_each(record, attribute, value)
  11     super(record, attribute, value.extend(WidthAsLength))
  12   end
  13 end