保存具有休眠子关系的Hibernate实体失败，并出现外键错误

Question

我受到侵犯-尝试保存休眠实体时找不到父键

我有上级实体：

@Entity
@Table(name = "parents")
public class Parent implements Serializable {
    private static final long serialVersionUID = 1246376778314918671L;

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "seq")
    @SequenceGenerator(name = "seq", sequenceName = "PARENT_ID_SEQ", allocationSize = 1)
    @Column(name = "parent_id")
    private long parentId;

    @Column(name = "display_name")
    @Size(min = 1, max = 128)
    @NotBlank   
    private String displayName;

    @JsonManagedReference("childAssignments")
    @OneToMany(mappedBy = "parent", fetch = FetchType.LAZY, cascade = CascadeType.ALL, orphanRemoval=true)
    private Set<ChildAssignment> childAssignments = new HashSet<ChildAssignment>(0);

    //regular getters and setters here
}

和子实体看起来像（在数据库中，它在Parents表中的parent_id字段上具有外键）：

Entity
@Table(name = "child_assignments")
public class ChildAssignment implements Serializable {
    private static final long serialVersionUID = -5949955576511639261L;

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "seq")
    @SequenceGenerator(name = "seq", sequenceName = "CHILD_ASSIGNMENT_ID_SEQ", allocationSize = 1)
    @Column(name = "child_assignment_id")
    private long childAssignmentId;

    @Column(name = "parent_id")  
    private long parentId;   // getting error because after creating new parent it has not been set

    @Column(name = "site_id")
    private long siteId;

    @ManyToOne
    @JoinColumn(name = "parent_id", insertable = false, updatable = false)
    private Parent parent;

    // regular getters and setters here

}

创建父对象和childAssignments对象后，我将childAssignment添加到父对象

ChildAssignment ca = new ChildAssignment();
ca.setSiteId(1);
// I do not set parent_id here since I do not know it and expecting Hibernate to figure it out

parent.getChildAssignments().add(childAssignment);
session.save(parent);

预期的结果是使用ID保存新的父项，然后使用该ID保存子项，但是在保存时似乎休眠状态不知道parent_id，我应该如何建立关联使其起作用？ 或对parent_id字段的一些注释？

更新

我试图删除childAssignment实体上的parent_id或将其设置为@Transient，并且出现新错误，无法将NULL插入表中，很明显，Hibernate尝试插入parent_id，但未填充它，

给孩子设置父母也无济于事

ChildAssignment ca = new ChildAssignment();
   ca.setSiteId(1);
   ca.setParent(parent)

   parent.getChildAssignments().add(childAssignment);
   session.save(parent);

我缺少什么？

解决了

我解决了更改childAssignment实体的问题

@Transient -- add transient (just to have it)
@Column(name = parent_id", insertable = false, updatable = false) -- add insertable and updatable  both equals to false
private parentId; 


.....

 @ManyToOne
 @JoinColumn(name = "parent_id") -- remove  insertable = false, updatable = false options
 private Parent parent;

Answer 1

您需要做：

ca.setParent(parent);

也一样

如果指定双向关系，则必须在Java代码中分配双方，就像纯Java一样。

其次，您对“ parentId”列的声明是多余的。 Hibernate会自动为您创建。