使用复合键映射/访问实体

Question

在我的应用程序中，我有 3 个核心类，如下所述。

public class Semana {

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

    private Integer series;

    private String observacao;

    private Integer ordenacao;


    @OneToMany(mappedBy = "semana")
    @JsonBackReference
    @OrderBy("ordenacao asc ")
    private List<TreinoOrdenado> treinoOrdenados;
 }

public class TreinoOrdenado {

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

    @ManyToOne
    @JoinColumn(name = "id_semana")
    private Semana semana;

    @ManyToOne
    @JoinColumn(name = "id_treino")
    private Treino treino; // can be repeated in the database but with different "ordenacao" 

    private Integer ordenacao;

}

@Table(name = "exercicio_ordenado")
public class ExercicioOrdenado {

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

    @ManyToOne
    @JoinColumn(name = "id_treino")
    @JsonBackReference
    @ToString.Exclude
    private Treino treino;

    @ManyToOne
    @JoinColumn(name = "id_exercicio")
    private Exercicio exercicio;

    private Integer ordenacao;

   @ManyToOne
   @JoinTable(name = "parametro")
   private Parametro parametro;

}

而这个 Parametro 类是这 3 个类之间的关系。

public class Parametro {

    @EmbeddedId
    private ParametroId parametroId = new ParametroId();

    @MapsId("semana")
    @OneToOne
    @JoinColumn(name = "semana_id")
    private Semana semana;

    @MapsId("treino")
    @OneToOne
    @JoinColumn(name = "treino_id")
    private TreinoOrdenado treino;

    @MapsId("exercicio")
    @OneToOne
    @JoinColumn(name = "exercicio_id")
    private ExercicioOrdenado exercicio;

    private Integer series;

    private String repeticoes;

    private String observacao;

}

public class ParametroId implements Serializable {

    @Column(name = "semana_id")
    private Long semana;

    @Column(name = "treino_id")
    private Long treino;

    @Column(name = "exercicio_id")
    private Long exercicio;

}

所以，这是我的问题。我希望能够从它的父类 ExercicioOrdenado 访问 Parametro，但是为了在数据库中区分，Parametro 类需要来自其他两个的引用（Semana , TreinoOrdenado)。

使用我当前的映射，我得到了这个错误：

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource 
[org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaConfiguration.class]: Invocation of init method failed; nested exception is org.hibernate.MappingException: Foreign key (FK73ewcy2r50kw71o4he51dkolv:parametro 
[parametro_exercicio_id,parametro_semana_id,parametro_treino_id])) must have same number of columns as the referenced primary key (parametro [id])

我可以通过以下方式将参数保存在数据库中：

   parametros.setSemana(semana);
   parametros.setExercicio(exercicioOrdenado);
   parametros.setTreino(treinoOrdenado);
   parametroRepository.save(parametros);

但我无法使用映射从 ExercicioOrdenado 检索。

我不知道这样做的正确方法。

Answer 1

我想我现在有办法……

为此，我们可以使用@Embeddable 和@EmbeddedId 注解。 在此链接中有示例。 https://www.baeldung.com/jpa-composite-primary-keys

@Entity
public class Parametro {

    @EmbeddedId
    private ParametroId parametroId;


    @OneToOne
    @JoinColumn(name = "exercicio_id")
    @ForeignKey(name = "fk_exercicio_id")
    private ExercicioOrdenado exercicio;    

    @OneToOne
    @JoinColumn(name = "semana_id")
    @ForeignKey(name = "fk_semana_id")
    private Semana semana;


    @OneToOne
    @JoinColumn(name = "treino_id")
    @ForeignKey(name = "fk_treino_id")
    private TreinoOrdenado treino;

    private Integer series;

    private String repeticoes;

    private String observacao;
}

@Embeddable
public class ParametroId {


    private log id;

    private log semana;


    private log treino;

    private log exercicio;

}

我相信这是使用 jpa 创建个性化主键的方法。我没有测试主键中实体的关系。我知道有不止一种形式可以做到这一点。

JPA @OneToOne with Shared ID -- Can I do this Better?