General rule is the following: If select contains single expression and it’s an entity, then result is that entity If select contains single expression and it’s a primitive, then result is that primitive If select contains multiple expressions, then result is Object[] containing the corresponding primitives/entities So, in your case list is a List<Object[]>.
As you said, the OpenSessionInView filter is very convenient in web applications. Regarding the limitations you mentioned: 1) Loading several lazy associations will result in multiple database transactions, a possible hit on performance. Yes, going to the DB often might lead to performance problems. Ideally you want to fetch all the data you need in … Read more
We are deprecating the Criteria API in lieu of JPA extension support. Consider this: CriteriaBuilder cb = entityManager.getCriteriaBuilder(); HibernateCriteria hc = cb.unwrap( HibernateCriteria.class ); … query.where( hc.someAwesomeThing( … ) ); List<SomeEntity> entities = entityManager.createQuery( query ).getResultList(); Contrary to comments, we do intend to continue to deliver Hibernate-specific features, but we want to introduce those through … Read more
You need to extend transaction boundaries to the boundaries of your test method. You can do it by annotating your test method (or the whole test class) as @Transactional: @Test @Transactional public void testInsert(){ long id=myService.addPerson(“JUNIT”); assertNotNull(id); if(id<1){ fail(); } } You can also use this approach to ensure that data was correctly written before … Read more
Remove the fetch=FetchType.EAGER. Eager fetching triggers cascading select statements. If you are using explicit HQL query e.g. “from User where something = someValue”, Hibernate will not respect the annotated Fetch mode. You would need to specify the join in the HQL query or the fetch mode in the criteria.
I think you should not use the hibernate session transactional methods, but let spring do that. Add this to your spring conf: <bean id=”txManager” class=”org.springframework.orm.hibernate3.HibernateTransactionManager”> <property name=”sessionFactory” ref=”mySessionFactory” /> </bean> <bean id=”transactionTemplate” class=”org.springframework.transaction.support.TransactionTemplate”> <property name=”transactionManager” ref=”txManager”/> </bean> and then I would modify your test method to use the spring transaction template: public static void main(String[] … Read more
This is a configuration I am using which keeps resources to a minimum. Of course you’ll want to tailor your application to use the resources it needs… Reference: http://www.mchange.com/projects/c3p0/index.html testConnectionOnCheckin validates the connection when it is returned to the pool. testConnectionOnCheckOut, although would ensure active connections before use, would be too expensive to do. idleConnectionTestPeriod … Read more
I use spring so we resolve it by org.springframework.dao.DataIntegrityViolationException try { ao_history_repository.save(new AoHistory(..)); } catch (DataIntegrityViolationException e) { System.out.println(“history already exist”); } But as @KevinGuancheDarias mention it: Please note that while this works. I suggest to solve the problem by issuing a findBy before the save, as this is messy, and I think it’s not … Read more
You can do something like @NamedQuery(name=”findWhatever”, query=”SELECT new path.to.dto.MyDto(e.id, e.otherProperty) FROM Student e WHERE e.id = ?1″) Then the MyDto object would just need a constructor defined with the correct fields i.e. public MyDto(String id, String otherProperty) { this.id = id; this.otherProperty = otherProperty; }
If you use @JsonBackReference on more than one getter/setter method in your project, you should distinguish them with a specific reference name. Maybe only one ‘defaultReference’ is allowed in the latest version? e.g In MovementView.java @JsonBackReference(value=”user-movement”) public User getUser() { return user; } In User.java @JsonManagedReference(value=”user-movement”) public MovementView getMovementView() { return movementView; }