Question

我正在使用Hibernate OGM和MongoDB，并拥有如下所示的实体：

@Entity
public class Card implements Serializable, Comparable<Card>
{
    private static Logger logger = LoggerFactory.getLogger(Card.class);

    @Id
    @GeneratedValue(generator = "uuid")
    @GenericGenerator(name = "uuid", strategy = "uuid2")
    private String  id;
    ...

    @OneToOne(cascade = {CascadeType.PERSIST, CascadeType.MERGE})
    private Card    cardRef;

    @OneToOne(mappedBy = "cardRef")
    private Card cardParent;

    // pinning : represents the owner's card
    @ManyToOne
    private Card cardPinOrigin;

    // List of the cards that have pinned the current
    @OneToMany(mappedBy = "cardPinOrigin")
    private List<Card> cardsPinned = new ArrayList<>();
    ...
}

当我通过卡片更新卡片来存储卡片时，可以使用卡片进行卡片制作。列表，它存储在数据库中：

＆＃39;父＆＃39;卡

{
    "_id" : "39d83887-e466-45c5-a5e8-1dfd5c22ed8a",
    "cardPinOrigin" : [ 
        {
            "id" : "478f6f83-161f-44dc-86c4-844f73084ffb"
        }
    ],
    ....
}

和＆＃39;孩子＆＃39;卡

{
    "_id" : "478f6f83-161f-44dc-86c4-844f73084ffb",
    "cardPinOrigin_id" : "39d83887-e466-45c5-a5e8-1dfd5c22ed8a",
    ...
}

我的问题是，当我从数据库中获取数据时，固定卡列表（cardsPinned java List）始终为空。有人知道为什么吗？

提前感谢您的回答。

Answer 1

使用@DBRef注释，它会创建另一个集合中的文档链接

@OneToOne(mappedBy = "cardRef")
@DBRef
private Card cardParent;

Hibernate OGM OneToMany自我参考

1 个答案: