使用Hibernate/JPA的@OneToOne映射中的外键字段为null

Question

我有两个实体,Document并BodyElement试图用Hibernate 4.2来坚持它们.mtdt_t填入正确的,但外键docid的mtdt_body_t表NULL.

我看到hibernate试图插入没有docid值.insert into mtdt_body_t values ( )

@Entity
@Table(name = "mtdt_t")
public class Document implements Serializable {

    @Id  
    @Column(name = "docid", unique = true, nullable = false)
    private String docid;

    @OneToOne(cascade = CascadeType.ALL, orphanRemoval = true, fetch = FetchType.EAGER)
    @OrderColumn
    @JoinColumn(name = "docid", nullable = false)
    private BodyElement bodyElement;

    public String getDocid() {
        return docid;
    }

    public void setDocid(String docid) {
        this.docid = docid;
    }

    public BodyElement getBodyElement() {
        return bodyElement;
    }

    public void setBodyElement(BodyElement bodyElement) {
        this.bodyElement = bodyElement;
    }

}

@Entity
@Table(name = "mtdt_body_t")
public class BodyElement implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @OneToOne
    @JoinColumn(name = "docid", insertable = false, updatable = false, nullable = false)
    private Document document;

    public BodyElement() {
    }

    public Long getId() {
        return id;
    }

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

    public Document getDocument() {
        return document;
    }

    public void setDocument(Document document) {
        this.document = document;
    }

}

我离开了另一个领域.在Document我有,

@OneToMany(cascade = CascadeType.ALL, orphanRemoval = true, fetch = FetchType.EAGER)
@OrderColumn
@JoinColumn(name = "docid", nullable = false)
@XmlPath("head/meta/kb:keywords/kb:keyword")
private Set<Keyword> keywords;

在Keyword类中我将外键映射为,

@ManyToOne
@JoinColumn(name = "docid", insertable = false, updatable = false, nullable = false)
@XmlTransient
private Document document;

那个docid领域永远不会NULL.

@OneToOne相比之下,Mapping 有什么特别之处@OneToMany吗？我只是模仿我@OneToMany在@OneToOne球场上所做的一切.

谢谢

Answer 1

\n

1. OrderColumn 注释在 OneToMany 或 ManyToMany 关系或元素集合上指定。OrderColumn 注释在引用要排序的集合的关系一侧指定。顺序列作为实体或可嵌入类的状态的一部分不可见。\n文档链接

\n

2. 您在映射时出错。您忘记了mappedBy 属性。这意味着实体之间的关系已经被映射，所以你不会这样做两次。您只需使用mappedBy 属性（下面是这篇文章）说“嘿，它在那里完成了” 。这是有用的示例：Hibernate \xe2\x80\x93 一对一示例（注释）

\n

\n