java - Spring-Data-Jpa 保存: Related entities saved as null which are not

Question

我有一个实体时间表:

@Entity @Table(name = TableUtils.TIMETABLE)public class Timetable {

private static final long serialVersionUID = -1307879048598194633L;

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = ColumnUtils.ID)
private long id;

@OneToMany(mappedBy = "timetable", cascade = {CascadeType.REMOVE, CascadeType.PERSIST})
private List<TimetableCell> timetableCells;

public List<TimetableCell> getTimetableCells() {
    return timetableCells;
}

public void setTimetableCells(List<TimetableCell> timetableCells) {
    this.timetableCells = timetableCells;
}
}

和一个实体 timetableCell:

@Entity
@Table(name = TableUtils.TIMETABLE_CELL)
public class TimetableCell extends AbstractElement {

private static final long serialVersionUID = -8083688091896353882L;

@ManyToOne(cascade = CascadeType.PERSIST)
@JoinColumn(name = ColumnUtils.WEEK_DAY_ID, nullable = false)
private WeekDay weekDay;

@ManyToOne(cascade = CascadeType.PERSIST)
@JoinColumn(name = ColumnUtils.LESSON_HOUR_ID, nullable = false)
private LessonHour lessonHour;

@ManyToOne(cascade = CascadeType.PERSIST)
@JoinColumn(name = ColumnUtils.TIMETABLE_ID, nullable = false)
private Timetable timetable;

...
}

首先，我使用 weekDay 和 LessonHours 创建时间表单元格。在我将此列表设置为时间表并尝试保存之后。但是所有时间表单元格都保存为 null weekDay 和 null LessonHour。 我调试了它。在保存之前，所有字段也已设置。

timetableRepository.save(timetable);

调试结果如下

Answer 1

1) timetableCells 仅标记有这些级联类型:

@OneToMany(mappedBy = "timetable", cascade = {CascadeType.REMOVE, CascadeType.PERSIST})

2) 周和小时部门只有这个:

@ManyToOne(cascade = CascadeType.PERSIST)

3) 如果你通过Timetable来保存这里的方法并且之前已经持久化了:

timetableRepository.save(timetable);

Spring Data JPA 不会调用persist，而是调用merge。

这可能就是级联不起作用的原因。如果将此添加到您的配置中，您可能会得到所需的东西:

cascade = {CascadeType.REMOVE, CascadeType.PERSIST, CascadeType.MERGE})