Spring Data JPA Projection com List Nested Projection

spring-data-projection-list-nested.java

// Temos primeiro as projections:

// CategoryProjection.java
public interface CategoryLoginProjection {

    String getName();
    String getCode();
    String getIconPath();
    List<SubcategoryLoginProjection> getSubcategories();
}

// SubcategoryProjection.java
public interface SubcategoryLoginProjection {

    String getName();
}

// Agora temos o nosso repository com uma JPQL query para buscar e filtrar as categorias, subcategorias e cursos
// e usando nossas projections:
// CategoryRepository.java


public interface CategoryRepository extends JpaRepository<Category, Long> {

    @Query(value = """
        select distinct c from Category c
        left join fetch c.subcategories s
        left join s.courses x
        where c.active = true and s.active = true and x.visible = true 
    """)
    List<CategoryLoginProjection> findCategoriesProjection();
}
           
// Veja mais sobre fetch na query:        
// https://stackoverflow.com/questions/5816417/how-to-properly-express-jpql-join-fetch-with-where-clause-as-jpa-2-criteriaq

Does it work?

Yes, it's working, but it may have unexpected behavior

Thanks for your reply

Won't this just result in proxies of the original objects? It would be interesting to see what happens if you give it Java records to populate as a DTO instead.