java - JPA实体字段引用OneToOne递归

Question

当我persist()我的实体时，我收到此错误。我认为错误的原因是关系，我的想法是FolderEntity(代表一个虚拟文件夹)可以留在另一个(只有一个)里面然后我创建了对self的引用(在扩展类中，因为所有资源都可以是在文件夹内，文件夹是资源)

org.hibernate.AnnotationException: Referenced property not a (One|Many)ToOne: com.editor.entity.FolderEntity.id in mappedBy of com.editor.entity.FolderEntity.folderId

这是我的主要实体:

@MappedSuperclass
public abstract class Entity implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "ID", nullable = false)
    private Integer id;

    /** getter/setter **/

}

然后我在我的 ResourceEntity 实体中扩展它:

@MappedSuperclass
public class ResourceEntity extends Entity {

    @Column(name = "NAME", length = Lengths.NAME40, unique = true, nullable = false)
    private String name;

    @Column(name = "DESCRIPTION", length = Lengths.DESCRIPTION1000, unique = false, nullable = true)
    private String description;

    @JoinColumn(name = "FOLDER_ID", updatable = true, nullable = false)
    @OneToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL, mappedBy = "id")
    private FolderEntity folderId;

    /** getter/setter **/

}

最后，我正在与这个实体合作:

@javax.persistence.Entity
@Table(name = "EDITOR_FOLDERS")
@NamedQueries({
        @NamedQuery(name = FolderEntity.ALL_FOLDERS, query = "select f from FolderEntity f"),
        @NamedQuery(name = FolderEntity.FOLDER_BY_NAME, query = "select f from FolderEntity f where name = :name and resourceType = :resourceType") })
public class FolderEntity extends ResourceEntity {


    public static final String ALL_FOLDERS = "findAllFolders";
    public static final String FOLDER_BY_NAME = "findAllFoldersByName";

    @Column(name = "RESOURCE_TYPE", length = Lengths.CODE, unique = false, nullable = false)
    private Integer resourceType;
    /** getter/setter **/

}

有人帮我解决这个问题吗？谢谢!

Answer 1

您应该检查 mappedBy 的含义:它不引用包含 ID 的字段(JPA 足够聪明，可以自己找到该字段)，但它引用另一个 XToOne “拥有”映射的字段

public abstract String mappedBy

(Optional) The field that owns the relationship. This element is only specified on the inverse (non-owning) side of the association.

(来自OneToOne的javadoc)

在您的情况下，您不需要mappedBy，因为您位于拥有方。您应该将属性命名为 folder，因为您引用的不是 ID，而是一个实体。

另一备注:如果您打算将应用程序中可能的值定义为常量，请使用 enum 表示 resourceType。