javax.ejb.EJBException：javax.persistence.PersistenceException：org.hibernate.exception.ConstraintViolationException：无法执行语句

Question

我无法理解我做错了什么

引起：com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException：列'USER_ID'不能为空

用户和文档 Id是自动增量... @GeneratedValue（strategy = GenerationType.IDENTITY）

public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    ..
}

... 要么 ......

public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
    ..
}

不要工作

@Stateless
@TransactionAttribute(TransactionAttributeType.NOT_SUPPORTED)
public class DocumentService implements Serializable {
    @Inject
    @LoggedIn
    private User currentUser;


    @TransactionAttribute(TransactionAttributeType.REQUIRES_NEW)
    public Document add(Document document) throws BusinessException {
        if (document.isTransient()) {
            System.out.println("dao " + currentUser); // print user correct
            document.setUser(currentUser);
        }
        System.out.println("dao " + d.getUser()); // print user correct
        return dao.save(document);
    }
}

@TransactionAttribute(TransactionAttributeType.NOT_SUPPORTED)
public class DAO<T extends BaseEntity> implements Serializable {

    private static final long serialVersionUID = 1L;
    private final Class<T> entityClass;
    private EntityManager entityManager;

    public DAO(Class<T> entityClass, EntityManager entityManager) {
        this.entityClass = entityClass;
        this.entityManager = entityManager;

    }

    @TransactionAttribute(TransactionAttributeType.MANDATORY)
    public T save(T entity) {

        Document d = (Document) entity;
        System.out.println("dao " + d.getUser()); // print user correct
        System.out.println("contains " + entityManager.contains(entity)); // return false
        if (entity.isNew()) {
            entityManager.persist(entity); // persist error USER_ID is null
            entityManager.flush();
        } else {
            entityManager.merge(entity);
        }

        return entity;
    }
}


public class Document {
    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Long id;
    @NotNull
    @ManyToOne
    private User user;
}
the relationship is unidirectional Document for User

---

栈.. 20：30：02,917 WARN [org.hibernate.engine.jdbc.spi.SqlExceptionHelper]（默认任务-6）SQL错误：1048，SQLState：23000 20：30：02,917 ERROR [org.hibernate.engine.jdbc.spi.SqlExceptionHelper]（默认任务-6）列'USER_ID'不能为空 20：30：02,930 ERROR [org.jboss.as.ejb3.invocation]（默认任务-6）JBAS014134：对于方法public com.taskboard.model.Document com.taskboard.boundary.DocumentService.save，组件DocumentService上的EJB调用失败（com.taskboard.model.Document）抛出com.taskboard.core.exception.BusinessException：javax.ejb.EJBException：javax.persistence.PersistenceException：org.hibernate.exception.ConstraintViolationException：无法执行语句