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Rémi C.'s questions

Martin Hope
Rémi C.
Asked: 2025-04-08 23:44:18 +0800 CST
  • 5

Quero fazer uma projeção no atributo de objeto de uma entidade com o Hibernate Criteria 6.

Aqui estão meus modelos:

    @Entity
    public class MyAuthor {
        private String id;
        private String name;
        private int nbBooks;
        private Date birthDate;
        @Embedded
        private MyAddress address;
    }

    @Embeddable
    public class MyAddress {
        private String street;
        private MyCity city;
    }

    @Entity
    public class MyCity {
       String id;
       String name;
    }

Aqui está meu teste de unidade:

    // We populate data with CITY_1 & CITY_2, ADDR_1 on CITY_1, ADDR_2 on CITY_1 and ADDR_3 on CITY_2 with @Before

    CriteriaBuilder criteriaBuilder = sessionFactory.getCurrentSession().getCriteriaBuilder();
    CriteriaQuery<MyCity> query = criteriaBuilder.createQuery(MyCity.class);
    Root<MyAuthor> root = query.from(MyAuthor.class);
    Join<MyAuthor, MyAddress> from = root.join("address", JoinType.LEFT);
    
    // produce this request : select c1_0.id,c1_0.name from MyAuthor ma1_0 left join MyCity c1_0 on c1_0.id=ma1_0.city_id where c1_0.name is not null
    query.select(from.get("city"))
        .where(criteriaBuilder.isNotNull(from.get("city").get("name")));
        
    // produce the same request : select c1_0.id,c1_0.name from MyAuthor ma1_0 left join MyCity c1_0 on c1_0.id=ma1_0.city_id where c1_0.name is not null
    // query.multiselect(from.get("city").get("id"), from.get("city").get("name"))
    // .where(criteriaBuilder.isNotNull(from.get("city").get("name")));


    // with the query.select(), there are 2 results, with the multiselect there are 3.
    List<MyCity> cities = sessionFactory.getCurrentSession().createQuery(query).getResultList();
    
    assertEquals(3, cities.size());

Não entendo como o SQL gerado é o mesmo MAS o comprimento do resultado é diferente.

Alguma ideia? Muito obrigado.

java