app/validators/normalized_uniqueness_validator.rb

   1 class NormalizedUniquenessValidator < ActiveModel::EachValidator
   2   def validate_each(record, attribute, value)
   3     relation = if options.fetch(:case_sensitive, true)
   4                  record.class.where("NORMALIZE(#{attribute}, NFKC) = NORMALIZE(?, NFKC)", value)
   5                else
   6                  record.class.where("LOWER(NORMALIZE(#{attribute}, NFKC)) = LOWER(NORMALIZE(?, NFKC))", value)
   7                end
   8
   9     relation = relation.where.not(record.class.primary_key => [record.id_in_database]) if record.persisted?
  10
  11     if relation.exists?
  12       error_options = options.except(:case_sensitive)
  13       error_options[:value] = value
  14
  15       record.errors.add(attribute, :taken, **error_options)
  16     end
  17   end
  18 end