Can I mix both update and insert in saveAll from JpaRepository

问题

I am using Spring Boot and Spring Data JPA and Hibernate as the persistence provider. I have extended my Repository interface with JPARepository. I have a list of Entity Bean for a table. Some of them already exist and some of them not.

I want to know what will happen when I call saveAll from my service layer and pass this List?

回答1:

If you look at the SimpleJpaRepository which is a common implementation of the CrudRepository you can see that it will simply invoke save for each of the elements:

@Transactional
public <S extends T> List<S> saveAll(Iterable<S> entities) {

    Assert.notNull(entities, "The given Iterable of entities not be null!");

    List<S> result = new ArrayList<S>();

    for (S entity : entities) {
        result.add(save(entity));
    }

    return result;
}

The save itself distinguishes itself whether to persist or merge the given entity:

@Transactional
public <S extends T> S save(S entity) {

    if (entityInformation.isNew(entity)) {
        em.persist(entity);
        return entity;
    } else {
        return em.merge(entity);
    }
}

So to answer your question.. yes you can mix both new and existing entities in the passes list.

来源：https://stackoverflow.com/questions/57551679/can-i-mix-both-update-and-insert-in-saveall-from-jparepository