Spring数据JPA中getReference方法的替代方法 [英] Alternatives to getReference method in Spring data JPA

问题描述

我发现自己在Spring Data JPA中难以实现可自定义的方法. 例如，我有一个Pet类，它有一个Owner(一对多).如果我有一个save(Pet pet, int ownerId)的方法，该怎么办.如何获得ownerId?使用Hibernate，我只能getReference这样

I found myself struggling to implement customizable methods in Spring Data JPA. For example, I have a Pet class, which has an Owner(Many to One rel.) What if I have a method to save(Pet pet, int ownerId). How can I get ownerId? Using Hibernate I just can getReference like that

public Pet save(Pet pet, int ownerId) {
        if (!pet.isNew() && get(pet.getId(), ownerId) == null) {
            return null;
        }
        pet.setUser(em.getReference(Owner.class, ownerId));
        if (pet.isNew()) {
            em.persist(pet);
            return pet;
        } else {
            return em.merge(pet);
        }
    }

但是使用Spring DJPA并不是那么容易.我创建了扩展JpaRepository < Pet, Integer >的接口，希望父类具有一个称为 saveWithReference，但我什么也没找到..有什么主意吗?

But using a Spring DJPA it's not so easy. I've created an interface that extends JpaRepository < Pet, Integer >, hoping that the parent class has a method called saveWithReference, but i didn't find anything.. Any ideas guys?

推荐答案

您应该同时具有PetRepository和OwnerRepository都扩展了JpaRepository.

You should have both a PetRepository and OwnerRepository both extending JpaRepository.

public interface PetRepository extends JpaRepository<Pet, Long> {}

和

public interface OwnerRepository extends JpaRepository<Owner, Long> {}

使用Spring Data JPA，您可以使用

Using Spring Data JPA you can use the getOne method to get a reference, this in contrast to the findOne which will actually query the database.

使用EntityManager编写的代码基本相同，应将其放在服务方法中，而不要直接使用EntityManager，请使用2个存储库.

The code you wrote using the EntityManager is basically the same and you should put that in a service method and instead of directly using the EntityManager use the 2 repositories.

@Service
@Transactional
public PetService {

    private final PetRepository pets;
    private final OwnerRepository owners;

    public PetService(PetRepository pets, OwnerRepository owners) {
        this.pets=pets;
        this.owners=owners;
    }

    public Pet savePet(Pet pet, long ownerId) {
        if (!pet.isNew() && get(pet.getId(), ownerId) == null) {
            return null;
        }
        pet.setUser(owners.getOne(ownerId));
        return pets.save(pet);
    }
}

类似的事情应该可以解决.无需在存储库中实现方法.

Something like that should do the trick. NO need to implement methods in your repository.

这篇关于Spring数据JPA中getReference方法的替代方法的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！