java - 从@OneToMany-association : CascadeType. ALL + orphanRemoval = true 中删除 child 不工作

Question

我很难从 OneToMany 关联中删除 child 。我的实体:

@Entity
@Table(name = "PERSON")
public class PersonEntity extends BaseVersionEntity<Long> implements Comparable<PersonEntity>
{
  ...
  // bi-directional many-to-one association to Project
  @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "person", orphanRemoval = true)
  private final Set<ProjectEntity> projects = new HashSet<ProjectEntity>();
  ...

@Entity
@Table(name = "PROJECT")
public class ProjectEntity extends BaseVersionEntity<ProjectPK>
{
  @EmbeddedId
  private ProjectPK id;
  ...
  // bi-directional many-to-one association to UdbPerson
  @ManyToOne(fetch = FetchType.LAZY)
  @JoinColumn(name = "PERSON_ID", nullable = false, insertable = false, updatable = false)
  private PersonEntity person;
  ...

@Embeddable
public class ProjectPK implements Serializable
{
  // default serial version id, required for serializable classes.
  private static final long serialVersionUID = 1L;

  @NotNull
  @Column(name = "PERSON_ID")
  private Long personId;
  ...

我删除 child 的失败尝试:

personEntity.getProjects().clear();

这可行，但我认为这不是正确的方法:

for (Iterator<ProjectEntity> iterator = personEntity.getProjects().iterator(); iterator.hasNext();)
{
  ProjectEntity projectEntity = iterator.next();
  projectDao.deleteEntity(projectEntity);
  iterator.remove();
}

我在这里做错了什么？

谢谢
强尼

Answer 1

关联是双向的，双向关联的拥有方是没有 mappedBy 属性的一方。这意味着在这种情况下，拥有方是项目方。

Hibernate 只考虑拥有方来知道关联是否存在。这意味着要打破一个人和一个项目之间的关联，你必须在项目中将这个人设置为null。