Spring Data JPA保存新实体并获取其所有依赖项

Question

我通过Spring Data Jpa save（）方法将我的实体保存到数据库中。此方法返回已保存的实体对象，但是如果Im保存新实体，则返回的对象不填充例如@manytomany完整实体。

public abstract class HelperPersistenceService<E extends AbstractEntity<I>, I extends Serializable> {

    @PersistenceContext
    private EntityManager entityManager;

    @Transactional
    public E saveWithMerge(E e) {
        if (e.getId() == null) {
            entityManager.persist(e);
        }
        return entityManager.merge(e);
    }

}

javax.persistence.TransactionRequiredException: No EntityManager with actual transaction available for current thread - cannot reliably process 'persist' call
    at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:278)
    at com.sun.proxy.$Proxy778.persist(Unknown Source)

如何解决那个问题？

Answer 1

您是否添加了cascade=persist,merge on many to many关系？

你追求的行为需要这种级联的存在。