finder_class = class_hierarchy.detect { |klass| !klass.abstract_class? }

          results = connection.select_all(
            construct_finder_sql(
              :select     => "#{finder_class.quoted_table_name}.#{attr_name}",
              :from       => "#{finder_class.quoted_table_name}",
              :conditions => [condition_sql, *condition_params]
            )
          )

          unless results.length.zero?
            found = true

            if configuration[:case_sensitive] && finder_class.columns_hash[attr_name.to_s].text?
              found = c.any? { |a| a[attr_name.to_s] == value }
            end

            record.errors.add(attr_name, configuration[:message]) if found
          end