没有主键ID的实体 [英] Entity without Primary Key ID

问题描述

我想创建一个没有ID的实体.

Hi I want to create an Entity which doesn't have an ID.

@Entity
@Table(name="USER_PROD_LIC_TYPE_ALL")
public class UserProdLicTypeAll {
   @EmbeddedId
   private UserProdLicTypeAllPK id;

   @ManyToOne(fetch=FetchType.LAZY)
    @JoinColumn(name="USER_ID")
    private User user;

    @ManyToOne(fetch=FetchType.LAZY)
    @JoinColumn(name="LICENSE_TYPE_ID") 
    private LicenseType licType;
    ....
  }

因为它没有主键，所以我创建了Embeddable类，如下所示:

since it doesn't have primary key i created Embeddable class as below:

 @Embeddable
 public class UserProdLicTypeAllPK {

  @ManyToOne(fetch=FetchType.LAZY)
  @JoinColumn(name="USER_ID")
  private User user;

  @ManyToOne(fetch=FetchType.LAZY)
  @JoinColumn(name="LICENSE_TYPE_ID")
  private LicenseType licType;
  ...
 }

这两个字段的组合返回唯一值. 但这是行不通的.我得到

The combination of these two fields returns a unique value. But it doesn't work. I get

org.springframework.beans.factory.UnsatisfiedDependencyException: exception.

我是否需要在User和LicenseType实体中对UserProdLicTypeAll和UserProdLicTypeAllPK进行引用?我也尝试过，但是仍然行不通.

Do i need to have references in User and LicenseType entities for both UserProdLicTypeAll and UserProdLicTypeAllPK? I have tried that also but still it doesn't work.

推荐答案

这是我的私人地狱.我不确定正确解决问题的最佳方法是什么.

This is my private hell. I'm not sure what the best way to solve it properly.

我最好的解决方案是:

@Entity
@Table(name = TableName.AREA_USER)
@IdClass(UserAreaPK.class)
public class UserArea implements Serializable {
    private static final long   serialVersionUID    = 1L;

    @Id
    @Column(name = UserAreaPK.C_AREA_ID)
    private Long areaId;

    @Id
    @Column(name = UserAreaPK.C_USER_ID)
    private String userId;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = UserAreaPK.C_AREA_ID, insertable = false, updatable = false)
    private Area area;

还有

/**
 * Primary key for the relationship  User-Area
 */
public class UserAreaPK implements Serializable {

    protected static final String   C_AREA_ID           = "area_id";
    protected static final String   C_USER_ID           = "user_id";
    private static final long       serialVersionUID    = 1L;

    @Id
    @Column(name = C_AREA_ID)
    private Long                    areaId;

    @Id
    @Column(name = C_USER_ID)
    private String                  userId;

这篇关于没有主键ID的实体的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！