实体管理器不会自动增加 ID

Question

我正在尝试运行 UT，但在 @Before 方法上失败了。 这是错误：

Caused by: org.h2.jdbc.JdbcSQLException: Unique index or primary key violation: "UK_PBNJJ4MCIQ51S0SJV9U3J2WQ4_INDEX_5 ON PUBLIC.XACTIVITYCONTENTTYPE(CONTENTTYPE_ID) VALUES (19, 1)"; SQL statement:
insert into XACTIVITYCONTENTTYPE (ACTIVITY_ID, CONTENTTYPE_ID) values (?, ?) [23505-197]

我有一个对象（ActivityEntity）数组，我正在初始化并保存在 H2 DB 中：

for (int i = 0; i < activities.length; i++) {
            Date createdDate = new Date();

            ActivityEntity activity = new ActivityEntity();
            activity.setType(ActivityType.valueOf(properties.getType()));
            activity.setLabel(ActivityLabel.valueOf(properties.getLabel()));
            activity.setStatus(Status.valueOf(properties.getStatus()));
            activity.setDeliveryType(DeliveryType.valueOf(properties.getDeliveryType()));
            activity.setSubject(em.find(SubjectEntity.class, subjectId));
            activity.setFontSize(FontSize.valueOf(properties.getFontSize()));
            activity.setEstimatedTime(ESTIMATED_TIME);
            activity.setPlannedTime(properties.getPlannedTime());
            activity.setInteractivityType(InteractivityType.valueOf(properties.getInteractivityType()));
            activity.setAudience(Audience.valueOf(properties.getAudience()));
            activity.setPurpose(Purpose.valueOf(properties.getPurpose()));
            activity.setAcademicLevel(AcademicLevel.valueOf(properties.getAcademicLevel()));
            activity.setEnvironment(Environment.valueOf(properties.getEnvironment()));
            activity.setInstructionMethod(InstructionMethod.valueOf(properties.getInstructionMethod()));
            activity.setCreatedBy(CREATED_BY);
            activity.setCreatedDate(createdDate);
            activity.setModifiedBy(CREATED_BY);
            activity.setModifiedDate(createdDate);
            activity.setDeprecated(properties.isDeprecated());
            activity.setTemplate(properties.isTemplate());
            activity.setCurriculumProvider(CurriculumProvider.valueOf(properties.getCurriculumProvider()));
            activity.setShowLessonNavigator(properties.isShowLessonNavigator());
            activity.setShowHeader(properties.isShowHeader());
            activity.setDisplayModuleType(properties.isDisplayModuleType());
            activity.setDisplayLabelType(properties.isDisplayLabelType());
            activity.setShowFooter(properties.isShowFooter());
            activity.setShowPagination(properties.isShowPagination());
            activity.setDisplayProgressBar(properties.isDisplayProgressBar());
            activity.setDisplayResources(properties.isDisplayResources());
            activity.setLanguage(language);
            activity.setPrimaryStatus(PrimaryStatus.valueOf(properties.getPrimaryStatus()));
            activity.setIntendedDeliveryType(IntendedDeliveryType.valueOf(properties.getIntendedDeliveryType()));
            activity.setNextGen(properties.isNextGen());
            activity.setExcludeFromSearch(properties.isExcludeFromSearch());
            activity.setExcludeFromRecommender(properties.isExcludeFromRecommender());
            activity.setTeacherCreated(properties.isTeacherCreated());
            activity.setTitle(TITLE + (i + 1), language);
            activity.getGrades().addAll(grades);
            activity.getStudentGroupings().add(new StudentGroupingEntity(properties.getStudentGroupingId()));
            activity.getPedagogicalIntents().add(new PedagogicalIntentEntity(properties.getPedagogicalIntentId()));
            activity.getLearnerTypes().add(new LearnerTypeEntity(properties.getLearnerTypeId()));
            activity.getContentTypes().add(new ContentTypeEntity(properties.getContentTypeId()));

            activities[i] = em.persist(activity);
        }
        em.flush();

最后一组是与错误相关的属性。 属性的 ContentTypeId 值为 19。 现在，这是 Activity 实体 class 的一部分：

    @Entity
    @Table(name = "ACTIVITY")
    public class ActivityEntity {
    
        @Id
        @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "SQ_ACTIVITY_ACTIVITY_ID")
        @SequenceGenerator(name = "SQ_ACTIVITY_ACTIVITY_ID", sequenceName = "SQ_ACTIVITY_ACTIVITY_ID", allocationSize = 1)
        @Column(name = "ACTIVITY_ID")
        private Integer id;
    
//MORE FIELDS LEFT OUT FOR CLARITY

    @ManyToMany
        @JoinTable(name = "XACTIVITYCONTENTTYPE", joinColumns = { @JoinColumn(name = "ACTIVITY_ID", referencedColumnName = "ACTIVITY_ID") }, inverseJoinColumns = { @JoinColumn(name = "CONTENTTYPE_ID", referencedColumnName="ID") } )
        private List<ContentTypeEntity> contentTypes = new ArrayList<>();
}

这是 ContentTypeEntity class：

@Entity
@Table(name = "CONTENTTYPE")
public class ContentTypeEntity {

    @Id
    @Column(name = "ID")
    private int id;

    @Column(name = "NAME")
    private String name;

    @Column(name = "SEQ_NUM")
    private int seqNum;
    
    public ContentTypeEntity() {
        
    }
    
    public ContentTypeEntity(int id) {
        this.id = id;
    }

    public int getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getSeqNum() {
        return seqNum;
    }

    public void setSeqNum(int seqNum) {
        this.seqNum = seqNum;
    }
    
}

如果我调试，将为我放入数组中的 3 个对象中的每一个正确生成 ActivityEntity 的 ID（ids=[1,2,3]）。 所以我不明白为什么第二个插入使用 id=1，这就是异常所暗示的。 如果我将一个 ActivityEntity 放入数组中，则一切正常。

Answer 1

您尚未粘贴所有代码，也无法分配 em.persist 的返回类型，但我认为问题可能与创建多个 id 为 19 的 contenttype 实例有关。

假设 id 为 19 的内容类型已经被持久化，并且您正试图创建对它的引用而不是持久化它，因为您的 ManyToMany 中没有级联，您可以像此示例测试代码所示那样执行类似的操作。 交易在那里，因为我不知道您的代码中的 tx 边界，只是为了单独保存内容类型

    @Test
    public void saveActivities() {
        // Tx1 - Persist content type

        EntityTransaction tx1 = em.getTransaction();
        tx1.begin();

        ContentTypeEntity contentType = new ContentTypeEntity(19);
        em.persist(new ContentTypeEntity(19));

        tx1.commit();

        em.detach(contentType);

        // Tx2 - Persist activities using a reference to content type

        EntityTransaction tx2 = em.getTransaction();
        tx2.begin();

        for (int i = 0; i < 3; i++) {

            ActivityEntity activity = new ActivityEntity();
            activity.getContentTypes().add(em.getReference(ContentTypeEntity.class, 19));

            em.persist(activity);
        }

        tx2.commit();

        // assertions
    }