一尘不染

Hibernate@OneToOne @NotNull

hibernate

它是有效申报@OneToOne,并@NotNull在关系的双方,如:

class ChangeEntry
{
    @OneToOne(cascade=CascadeType.ALL)
    @NotNull
    ChangeEntryDetails changeEntryDetails;

    public void addDetails(ChangeEntryDetails details) {
       this.changeEntryDetails = details;
       details.setChangeEntry(this);
    }
 }

 class ChangeEntryDetails
 {
     @OneToOne(cascase=CascadeType.ALL)
     @NotNull
     ChangeEntry changeEntry;

     public void setChangeEntry(ChangeEntry changeEntry)
     {
          this.changeEntry = changeEntry;
     }
 }

我找不到任何表明这是无效的信息,但似乎在持久性过程中,至少必须违反关系的一侧。(例如,如果首先写入changeEntry,则changeEntryDetails临时为null)。

尝试此操作时,我看到抛出了异常not-null property references a null or transient value

我想避免在可能的情况下放宽约束,因为双方都 必须 存在。


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2020-06-20

共1个答案

一尘不染

声明@OneToOne@NotNull在关系的两边是否合法(…)我找不到任何表明无效的内容,但是在持久性过程中,似乎至少必须违反关系的一侧。(例如,如果changeEntry先写,changeEntryDetails则暂时为null)。

这是有效的,并且在正确映射的实体上一切正常。您需要将双向关联的一侧声明为“拥有”侧(此“控制”插入顺序)。一种可行的解决方案:

@Entity
@NamedQueries( { @NamedQuery(name = ChangeEntry.FIND_ALL_CHANGEENTRIES, query = "SELECT c FROM ChangeEntry c") })
public class ChangeEntry implements Serializable {
    public final static String FIND_ALL_CHANGEENTRIES = "findAllChangeEntries";

    @Id
    @GeneratedValue
    private Long id;

    @OneToOne(optional = false, cascade = CascadeType.ALL)
    @JoinColumn(name = "DETAILS_ID", unique = true, nullable = false)
    @NotNull
    private ChangeEntryDetails changeEntryDetails;

    public void addDetails(ChangeEntryDetails details) {
        this.changeEntryDetails = details;
        details.setChangeEntry(this);
    }

    // constructor, getters and setters
}

对于其他实体(请注意mappedBy在关联的非所有权方设置的属性):

@Entity
public class ChangeEntryDetails implements Serializable {
    @Id
    @GeneratedValue
    private Long id;

    @OneToOne(optional = false, mappedBy = "changeEntryDetails")
    @NotNull
    private ChangeEntry changeEntry;

    // constructor, getters and setters
}

对于这些实体,以下测试(用于演示目的)通过:

public class ChangeEntryTest {
    private static EntityManagerFactory emf;    
    private EntityManager em;

    @BeforeClass
    public static void createEntityManagerFactory() {
        emf = Persistence.createEntityManagerFactory("TestPu");
    }    
    @AfterClass
    public static void closeEntityManagerFactory() {
        emf.close();
    }    
    @Before
    public void beginTransaction() {
        em = emf.createEntityManager();
        em.getTransaction().begin();
    }    
    @After
    public void rollbackTransaction() {   
        if (em.getTransaction().isActive()) {
            em.getTransaction().rollback();
        }
        if (em.isOpen()) {
            em.close();
        }
    }

    @Test 
    public void testCreateEntryWithoutDetails() {
        try {
            ChangeEntry entry = new ChangeEntry();
            em.persist(entry);
            fail("Expected ConstraintViolationException wasn't thrown.");
        } catch (ConstraintViolationException e) {
            assertEquals(1, e.getConstraintViolations().size());
            ConstraintViolation<?> violation = e.getConstraintViolations()
                .iterator().next();

            assertEquals("changeEntryDetails", violation.getPropertyPath()
                .toString());
            assertEquals(NotNull.class, violation.getConstraintDescriptor()
                .getAnnotation().annotationType());
        }
    }

    @Test
    public void testCreateDetailsWithoutEntry() {    
        try {
            ChangeEntryDetails details = new ChangeEntryDetails();
            em.persist(details);
            fail("Expected ConstraintViolationException wasn't thrown.");
        } catch (ConstraintViolationException e) {
            assertEquals(1, e.getConstraintViolations().size());
            ConstraintViolation<?> violation = e.getConstraintViolations()
                .iterator().next();

            assertEquals("changeEntry", violation.getPropertyPath()
                .toString());
            assertEquals(NotNull.class, violation.getConstraintDescriptor()
                .getAnnotation().annotationType());
        }
    }

    @Test
    public void validEntryWithDetails() {
        ChangeEntry entry = new ChangeEntry();
        ChangeEntryDetails details = new ChangeEntryDetails();
        entry.addDetails(details);
        em.persist(entry);

        Query query = em.createNamedQuery(ChangeEntry.FIND_ALL_CHANGEENTRIES);
        assertEquals(1, query.getResultList().size());
    }
}
2020-06-20