# File lib/dm-validations/validators/uniqueness_validator.rb, line 27
      def valid?(target)
        value = target.validation_property_value(field_name)
        return true if optional?(value)

        opts = {
          :fields    => target.model.key,
          field_name => value,
        }

        Array(@options[:scope]).each { |subject| opts[subject] = target.__send__(subject) }

        resource = DataMapper.repository(target.repository.name) { target.model.first(opts) }

        return true if resource.nil?

        target.saved? && resource.key == target.key
      end