Question

我在用户和评论之间有很多关系。它的工作原理是用户只能发表一条评论。我需要添加另一个生成的ID，使密钥唯一。

评论类

 @Entity
@IdClass(CommentPK.class)
public class Comment {
    @Id
    private Long id;


    @Id
    @ManyToOne
    @JoinColumn(name = "gameID" ,referencedColumnName = "id")
    private Game game;

    @Id
    @ManyToOne
    @JoinColumn(name = "userID",referencedColumnName = "id")
    private User user;

    private String Text;

    public Comment() {
        super();
        this.id = null;
        this.game = null;
        this.user = null;
        Text = null;
    }
    public Comment(Game game, User user, String text) {
        this();
        this.id = null;
        this.game = game;
        this.user = user;
        Text = text;
    }
    public Comment(Game game, String text) {
        this();
        this.id = null;
        this.game = game;
        this.Text = text;
    } }//setters and getters

CommentPK

public class CommentPK implements Serializable {
@GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    private Long game;

    private Long user; }//setters and getters

错误并非全部都很大

Can not set java.lang.Long field guru.springframework.domain.CommentPK.game to guru.springframework.domain.TF_Game

没有生成的ID，它工作正常。

Answer 1

正如我在您的代码中看到的，错误消息指出类型在idClass和实体之间不匹配。

如你所见，你的idclass有Long，Long，Long作为类型，而你的实体有Long，Game，User。或许尝试以下

 @Entity
 @IdClass(CommentPK.class)
 public class Comment {
@Id
private Long id;

@Id
@Column(name="gameID")
private Long gameId;

@ManyToOne
@JoinColumn(name = "gameID" ,referencedColumnName = "id", insertable=false, updatable=false)
private Game game;

@Id
@Column(name="userID")
private Long userId;

@ManyToOne
@JoinColumn(name = "userID",referencedColumnName = "id", insertable=false, updatable=false)
private User user;

private String Text;

并根据实体中的属性重命名IdClass中的字段。

带有3个主键的Spring jpa数据jpa复合使用IdClass

1 个答案: