validate_each

# File activerecord/lib/active_record/validations/uniqueness.rb, line 19
      def validate_each(record, attribute, value)
        finder_class = find_finder_class_for(record)
        value = map_enum_attribute(finder_class, attribute, value)

        return if record.persisted? && !validation_needed?(finder_class, record, attribute)

        relation = build_relation(finder_class, attribute, value)
        if record.persisted?
          if finder_class.primary_key
            relation = relation.where.not(finder_class.primary_key => [record.id_in_database])
          else
            raise UnknownPrimaryKey.new(finder_class, "Cannot validate uniqueness for persisted record without primary key.")
          end
        end
        relation = scope_relation(record, relation)

        if options[:conditions]
          conditions = options[:conditions]

          relation = if conditions.arity.zero?
            relation.instance_exec(&conditions)
          else
            relation.instance_exec(record, &conditions)
          end
        end

        if relation.exists?
          error_options = options.except(:case_sensitive, :scope, :conditions)
          error_options[:value] = value

          record.errors.add(attribute, :taken, **error_options)
        end
      end