使用“Spring Data Jpa 查询”检索“休眠代理对象”列表

Question

Can I somehow retrieve a list of Hibernate proxy objects with Spring Data Jpa query?

I have object ids from request, and I don't want to retrieve them (because there are many OneToOne relations in entity), but I want to retrieve their proxies which will contain their ids ( I need this for relation ). I want something like Hibernate findOne() or getOne() but for list result.

Any suggestion will be appreciated, thanks!

Answer 1

If I get your questions right you want to do something like this:

Geo-spatial repository queries (does not require @Query annotation)

public interface PersonRepository extends JpaRepository<Person, String>
List<Person> findByLocationNear(String location, Integer distance);
List<Person> findByCity(String city);
}

However You may also use JQL Query Methods in you repository

@Query("SELECT p FROM Person t WHERE p.name =?1 AND p.location=?2 ") 
List<Person> findPersonByLocation(String fName, String location);

Also, you may use HQL

Answer 2

The correct solution is using an EntityManager instance.

entityManager.getReference(YourClass.class, id);

Being that this method accepts only a single ID, you'd need to write a custom SQL query (using HQL or native SQL ) to retrieve only the IDs of the needed objects.

Having a List<T> ids , you can than

final List<YourClass> proxyValues = 
         ids.stream()
            .map(id -> entityManager.getReference(YourClass.class, id))
            .collect(Collectors.toList());

Speaking about performance, this is perfectly fine, as the database access would be done a single time, retrieving a small amount of data.