在JPA/Hibernate中具有继承的EntityGgraph或Join Fetch

Question

我正在用JpaRepository处理JPA/Hibernate实体。我有几个实体与@OneToOne和@OneToMore关系。为了使代码简短，我将实体命名为A、B、C、D等。. A是根实体，链下有继承与连接策略。请看下面的代码-

A.java

@Entity
@Table(name = "A")
public class A {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long aId;

    @Column
    private String name;

    @OneToOne
    @JoinColumn(name = "bId")
    private B b;

    @OneToMany(mappedBy = "a")
    private Set<C> cSet;
    
    // other entity specific fields
    // getters and setters
}

B.java

@Entity
@Table(name = "B")
public class B {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long bId;

    // other entity specific fields
    // getters and setters
}

C.java

@Entity
@Table(name = "C")
public class C {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long cId;

    @ManyToOne
    @JoinColumn(name = "aId", referencedColumnName = "aId")
    private A a;

    @OneToMany(mappedBy = "c")
    private Set<D> dSet;

    // other entity specific fields
    // getters and setters
}

D. java

@Entity
@Table(name = "D")
@Inheritance(strategy = InheritanceType.JOINED)
public class D {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long dId;

    @ManyToOne
    @JoinColumn(name = "cId", referencedColumnName = "cId")
    private C c;

    @OneToMany(mappedBy = "d")
    private Set<E> eSet;

    // other entity specific fields
    // getters and setters

}

E.java

@Entity
@Table(name = "E")
public class E {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long eId;

    @ManyToOne
    @JoinColumn(name = "dId", referencedColumnName = "dId")
    private D d;

    // other entity specific fields
    // getters and setters
}

f. java

@Entity
@Table(name = "F")
public class F extends D {

    @OneToMany(mappedBy = "d")
    private Set<H> hSet;

    // other entity specific fields
    // getters and setters
}

G.java

@Entity
@Table(name = "G")
public class G extends D {

    @OneToMany(mappedBy = "d")
    private Set<I> iSet;

    // other entity specific fields
    // getters and setters
}

H.java

@Entity
@Table(name = "H")
public class H {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long hId;

    @ManyToOne
    @JoinColumn(name = "dId", referencedColumnName = "dId")
    private D d;

    // other entity specific fields
    // getters and setters
}

I.java

@Entity
@Table(name = "I")
public class I {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long iId;

    @ManyToOne
    @JoinColumn(name = "dId", referencedColumnName = "dId")
    private D d;

    // other entity specific fields
    // getters and setters
}

如果您看到继承从实体D作为父实体开始，那么G和F扩展了D。我需要通过EnityGraph或Join fetch获取所有实体。所有的联想都是懒惰的。我有根A的id。当我调用<代码>正向。findById（援助）

我尝试了许多解决方案，但我无法获取。创建实体图的问题是实体链之间的继承。我能够获取的唯一方法是当我创建EAGER关联时。我不想将@OneTo很多映射设置为EAGER。

有人能给我推荐一个执行这项任务的解决方案（无论是@EntityGraph还是Join Fetch）吗？

Answer 1

这似乎与这里的问题非常相似：https://stackoverflow.com/a/61272573/412446

我想你可以推断出实体图不能用于此。如果需要的话，可以使用join-fetch，但我认为Spring数据JPA存储库只能处理实体图。不过，您仍然可以使用Blaze持久性实体视图：）