在hibernate和spring中加入交叉引用表

Question

我使用休眠和弹簧数据。有两个具有多对多关系的表。

@Entity
@Table(name = "FirstEntity")
public class FirstEntity {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "first_entity_id")
    private Long id;

    @Column(name = "first_entiry_name")
    private String name;

    /* getters and setters are below*/
}

@Entity
@Table(name = "SecondEntity")
public class SecondEntity {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "second_entity_id")
    private Long id;

    @Column(name = "second_entiry_name")
    private String name;

    @Column(name = "second_entiry_desc")
    private String description;

    /* getters and setters are below*/
}

以及用于交叉引用表的实体。

@Entity
@Table(name = "FirstSecondEntity")
public class FirstSecondEntity {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "first_second_entity_id")
    private Long id;

    @Column(name = "first_entity_id")
    private Long firstEntityId;

    @Column(name = "second_entity_id")
    private Long secondEntityId;

    /* getters and setters are below*/
}

我需要这样的选择

SELECT FirstEntity.name, SecondEntity.name, SecondEntity.description FROM SecondEntity INNER JOIN FirstSecondEntity ON SecondEntity.id = FirstSecondEntity.secondEntityId INNER JOIN User ON FirstEntity.id = FirstSecondEntity.firstEntityId

即我需要来自交叉引用表的所有记录，而不是 ids，而是来自实体的实际信息。 将此查询插入到我的 CrudRepository 扩展类中的 @Query 注释中不起作用，因为

ERROR [main][org.hibernate.hql.internal.ast.ErrorCounter]  Path expected for join!

所以我需要你的帮助。

Answer 1

您的连接表完全搞砸了。在这种情况下，您实际上甚至不需要将连接表作为休眠映射：

在第二个实体中添加以下列表：

@ManyToMany(fetch = FetchType.LAZY)
@JoinTable(name = "FirstSecondEntity",
        joinColumns = {
                @JoinColumn(name = "first_entity_id",
                        nullable = false,
                        updatable = false) },
        inverseJoinColumns = {
                @JoinColumn(name = "second_entity_id",
                        nullable = false,
                        updatable = false) },
        )
private List<FirstEntity> firstEntities;

在 FirstEntity 中添加以下列表：

@ManyToMany(fetch = FetchType.LAZY,
        mappedBy = "firstEntities")
private List<SecondEntity> secondEntities;