Jpa - Hibernate ManyToMany 将许多插入到连接表中

Question

我遵循WorkDay（有注释ManyToMany）和Event之间的ManyToMany关系

工作日实体

@Entity
@Table(name = "WORK_DAY", uniqueConstraints = { @UniqueConstraint(columnNames = { "WORKER_ID", "DAY_ID" }) })
@NamedQueries({
        @NamedQuery(name = WorkDay.GET_WORK_DAYS_BY_MONTH, query = "select wt from WorkDay wt where wt.worker = :worker and to_char(wt.day.day, 'yyyyMM') = :month) order by wt.day"),
        @NamedQuery(name = WorkDay.GET_WORK_DAY, query = "select wt from WorkDay wt where wt.worker = :worker and wt.day = :day") })
public class WorkDay extends SuperClass {

    private static final long serialVersionUID = 1L;

    public static final String GET_WORK_DAYS_BY_MONTH = "WorkTimeDAO.getWorkDaysByMonth";
    public static final String GET_WORK_DAY = "WorkTimeDAO.getWorkDay";

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "WORKER_ID", nullable = false)
    private Worker worker;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "DAY_ID", nullable = false)
    private Day day;

    @Column(name = "COMING_TIME")
    @Convert(converter = LocalDateTimeAttributeConverter.class)
    private LocalDateTime comingTime;

    @Column(name = "OUT_TIME")
    @Convert(converter = LocalDateTimeAttributeConverter.class)
    private LocalDateTime outTime;

    @Enumerated(EnumType.STRING)
    @Column(name = "STATE", length = 16, nullable = false)
    private WorkDayState state = WorkDayState.NO_WORK;

    @ManyToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
    @JoinTable(name = "WORK_DAY_EVENT", joinColumns = {
            @JoinColumn(name = "WORK_DAY_ID", nullable = false)}, inverseJoinColumns = {
            @JoinColumn(name = "EVENT_ID", nullable = false)})
    @OrderBy(value = "startTime desc")
    private List<Event> events = new ArrayList<>();

    protected WorkDay() {
    }

    public WorkDay(Worker worker, Day day) {
        this.worker = worker;
        this.day = day;
        this.state = WorkDayState.NO_WORK;
    }
}

事件实体

@Entity
@Table(name = "EVENT")
public class Event extends SuperClass {

    @Column(name = "DAY", nullable = false)
    @Convert(converter = LocalDateAttributeConverter.class)
    private LocalDate day;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "TYPE_ID", nullable = false)
    private EventType type;

    @Column(name = "TITLE", nullable = false, length = 128)
    private String title;

    @Column(name = "DESCRIPTION", nullable = true, length = 512)
    private String description;

    @Column(name = "START_TIME", nullable = false)
    @Convert(converter = LocalDateTimeAttributeConverter.class)
    private LocalDateTime startTime;

    @Column(name = "END_TIME", nullable = true)
    @Convert(converter = LocalDateTimeAttributeConverter.class)
    private LocalDateTime endTime;

    @Enumerated(EnumType.STRING)
    @Column(name = "STATE", nullable = false, length = 16)
    private EventState state;

    protected Event() {
    }
}

为清晰起见附上 UI 表单

当我第一次用运行图标推送时钟时，在bean中表示“创建事件并开始工作日”，调用以下方法：

public void startEvent() {
    stopLastActiveEvent();
    Event creationEvent = new Event(workDay.getDay().getDay(), selectedEventType, selectedEventType.getTitle(),
            LocalDateTime.now());
    String addEventMessage = workDay.addEvent(creationEvent);
    if (Objects.equals(addEventMessage, "")) {
        em.persist(creationEvent);
        if (workDay.isNoWork()
                && !creationEvent.getType().getCategory().equals(EventCategory.NOT_INFLUENCE_ON_WORKED_TIME)) {
            startWork();
        }
        em.merge(workDay);
    } else {
        Notification.warn("Невозможно создать событие", addEventMessage);
    }
    cleanAfterCreation();
}

public String addEvent(Event additionEvent) {
    if (!additionEvent.getType().getCategory().equals(NOT_INFLUENCE_ON_WORKED_TIME)
            && isPossibleTimeBoundaryForEvent(additionEvent.getStartTime(), additionEvent.getEndTime())) {
        events.add(additionEvent);
        changeTimeBy(additionEvent);
    } else {
        return "Пересечение временых интервалов у событий";
    }
    Collections.sort(events, new EventComparator());
    return "";
}

private void startWork() {
    workDay.setComingTime(workDay.getLastWorkEvent().getStartTime());
    workDay.setState(WorkDayState.WORKING);
}

在日志中我看到：

1. 插入事件表
2. 更新工作日表
3. 插入到 work_day_event 表中

在 UI 上仅更新附加框架。看起来总是很好.. 当前WorkDay 对象在events 集合中有一个元素，所有数据也都插入到DB.. 但如果这次编辑事件行

事件行监听器：

public void onRowEdit(RowEditEvent event) {
    Event editableEvent = (Event) event.getObject();
    LocalDateTime startTime = fixDate(editableEvent.getStartTime(), editableEvent.getDay());
    LocalDateTime endTime = fixDate(editableEvent.getEndTime(), editableEvent.getDay());
    if (editableEvent.getState().equals(END) && startTime.isAfter(endTime)) {
        Notification.warn("Невозможно сохранить изменения", "Время окончания события больше времени начала");
        refreshEvent(editableEvent);
        return;
    }
    if (workDay.isPossibleTimeBoundaryForEvent(startTime, endTime)) {
        editableEvent.setStartTime(startTime);
        editableEvent.setEndTime(endTime);
        workDay.changeTimeBy(editableEvent);
        em.merge(workDay);
        em.merge(editableEvent);
    } else {
        refreshEvent(editableEvent);
        Notification.warn("Невозможно сохранить изменения", "Пересечение временых интервалов у событий");
    }
}

到work_day_event 插入具有相同work_day_id 和event_id 数据的新行。如果编辑行，则再进行一次插入等。结果，我在work_day_event 表中有几行相等的行。为什么会这样？

link to github project repository(look ver-1.1.0-many-to-many-problem branch)

Answer 1

将WorkDay entity 中的events 的CascadeType.ALL 更改为CascadeType.MERGE

使用此代码

@ManyToMany(fetch = FetchType.LAZY, cascade = CascadeType.MERGE)

而不是

@ManyToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL)

---

不要使用ArrayList，使用HashSet。因为ArrayList 允许重复。

有关 CasecadeType 的更多信息，请按照教程进行操作：

1. Hibernate JPA Cascade Types
2. Cascading best practices

Answer 2

我认为简单的解决方案是删除多对多关系的级联并手动完成工作！ .无论如何，我看到您已经在做多余的事情了。所以试着删除你的 CascadeType.ALL

@ManyToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL)

How to persist @ManyToMany relation - duplicate entry or detached entity