How to fetch a one-to-many DTO projection with JPA and Hibernate

Introduction In this article, I’m going to show you how you can fetch a one-to-many relationship as a DTO projection when using JPA and Hibernate. While entities make it very easy to fetch additional relationships, when it comes to DTO projections, you need to use a ResultTransformer to achieve this goal.

The best way to use a Hibernate ResultTransformer

Introduction In this article, I’m going to present the best way to use a Hibernate ResultTransformer so that you can customize the result set of a given JPA or Hibernate query. As I already explained, the Hibernate ResultTransformer is a very powerful mechanism, allowing you to customize a JPQL, Criteria API, or native SQL query result set in any possible way.

Why you should use the Hibernate ResultTransformer to customize result set mappings

Introduction JPA queries allow you to fetch either entities or DTO projections. However, sometimes you want a combined result set as illustrated in this Hibernate forum question.