Hibernate中的复合自引用外键映射

Question

我有以下MySQL表。这里的思想是轨道和课程是主键。并且轨道中的一个航向可能依赖于“同一轨道”中的另一个航向，因此我在(track_id,depends_on_course_id)上创建了一个复合FK

CREATE  TABLE IF NOT EXISTS `testdb_1`.`track_course` (
`track_id` INT UNSIGNED NOT NULL ,
`course_id` INT UNSIGNED NOT NULL ,
`depends_on_course_id` INT UNSIGNED NULL ,
PRIMARY KEY (`track_id`, `course_id`) ,
INDEX `tc_tbl_dependent_crs_fk_idx` (`track_id` ASC, `depends_on_course_id` ASC) ,
CONSTRAINT `tc_tbl_dependent_crs_fk`
FOREIGN KEY (`track_id` , `depends_on_course_id` )
REFERENCES `testdb_1`.`track_course` (`track_id` , `course_id` ))

@Entity
@Table(name = "track_course", catalog = "testdb_1")
public class TrackCourse implements java.io.Serializable {

    private TrackCourseId id;
    private TrackCourse trackCourse;
    private Set<TrackCourse> trackCourses = new HashSet<TrackCourse>(0);

    public TrackCourse() {
    }

    public TrackCourse(TrackCourseId id, TrackCourse trackCourse) {
        this.id = id;
        this.trackCourse = trackCourse;
    }

    public TrackCourse(TrackCourseId id, TrackCourse trackCourse,
            Set<TrackCourse> trackCourses) {
        this.id = id;
        this.trackCourse = trackCourse;
        this.trackCourses = trackCourses;
    }

    @EmbeddedId
    @AttributeOverrides({
            @AttributeOverride(name = "trackId", column = @Column(name = "track_id", nullable = false)),
            @AttributeOverride(name = "courseId", column = @Column(name = "course_id", nullable = false)) })
    public TrackCourseId getId() {
        return this.id;
    }

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

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumns({
            @JoinColumn(name = "track_id", referencedColumnName = "track_id", insertable = false, updatable = false),
            @JoinColumn(name = "depends_on_course_id", referencedColumnName = "course_id", insertable = false, updatable = false) })
    public TrackCourse getTrackCourse() {
        return this.trackCourse;
    }

    public void setTrackCourse(TrackCourse trackCourse) {
        this.trackCourse = trackCourse;
    }

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "trackCourse", cascade= CascadeType.ALL)
    public Set<TrackCourse> getTrackCourses() {
        return this.trackCourses;
    }

    public void setTrackCourses(Set<TrackCourse> trackCourses) {
        this.trackCourses = trackCourses;
    }

}

TrackCourse tc1 = new TrackCourse(new TrackCourseId(11, 1), null);
TrackCourse tc2 = new TrackCourse(new TrackCourseId(11, 2), tc1);
TrackCourse tc4 = new TrackCourse(new TrackCourseId(11, 4), tc1);

Set<TrackCourse> trackCourses = new HashSet<TrackCourse>();
trackCourses.add(tc2);
trackCourses.add(tc4);
tc1.setTrackCourses(trackCourses);
session.save(tc1); // I expect this statement to create three rows with following values

track_id    course_id   depends_on_course_id
11,         1,          null
11          2           1
11          4           1

但我在“depends_on_course_id column”中得到的结果都是空的，我猜getTrackCourse方法的映射有问题，但我不知道是什么？非常感谢任何帮助。

Answer 1

getTrackCourse（）似乎有空的cascadeType，因此默认情况下不会层叠任何操作。

顺便说一句。我建议使用生成键而不是自然键，这会使事情更加复杂。