java - 在 Hibernate 中使用 native SQL 查询将结果集放入 DTO

Question

我有如下查询

select f.id, s.name, ss.name
from first f
left join second s on f.id = s.id
left join second ss on f.sId = ss.id

如果我可以使用 HQL，我会使用 HQL constructor syntax直接用结果集填充 DTO。 但是，由于 hibernate 不允许在没有关联的情况下进行左连接，因此我必须使用 native SQL 查询。

目前我正在以 JDBC 样式循环结果集并填充 DTO 对象。 有没有更简单的方法来实现它？

Answer 1

您也许可以使用结果转换器。报价 Hibernate 3.2: Transformers for HQL and SQL :

SQL Transformers

With native sql returning non-entity beans or Map's is often more useful instead of basic Object[]. With result transformers that is now possible.

List resultWithAliasedBean = s.createSQLQuery(
  "SELECT st.name as studentName, co.description as courseDescription " +
  "FROM Enrolment e " +
  "INNER JOIN Student st on e.studentId=st.studentId " +
  "INNER JOIN Course co on e.courseCode=co.courseCode")
  .addScalar("studentName")
  .addScalar("courseDescription")
  .setResultTransformer( Transformers.aliasToBean(StudentDTO.class))
  .list();

StudentDTO dto =(StudentDTO) resultWithAliasedBean.get(0);

Tip: the addScalar() calls were required on HSQLDB to make it match a property name since it returns column names in all uppercase (e.g. "STUDENTNAME"). This could also be solved with a custom transformer that search the property names instead of using exact match - maybe we should provide a fuzzyAliasToBean() method ;)

引用文献

• hibernate 引用指南
  • 16.1.5. Returning non-managed entities
• Hibernate 的博客
  • Hibernate 3.2: Transformers for HQL and SQL