Orm 帮助在JPA2.0中映射复合外键

我是JPA的新手，我正在尝试映射一个遗留数据库。文件单独正确加载，但关系无法正常工作。任何帮助都将不胜感激

Java

@Entity
@IdClass(ParentKey.class)
public class Parent {
    @Id
    @Column(name="code")
    private String code;

    @Id
    @Column(name="id")
    private int id;

    @OneToMany(mappedBy="parent")
    private List<Child> children = new ArrayList<Child>();
}

public class ParentKey {
    private String code;
    private int id;
}

@Entity
@IdClass(ChildKey.class)
public class Child {
    @Id
    @JoinColumns({
        @JoinColumn(name="code")
        @JoinColumn(name="id")
    })
    private Parent parent;

    @Id
    @Column(name="index")
    private int index;
}

public class ChildKey {
    private String code;
    private int id;
    private int index;
}

编辑1：

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添加ChildKey和ParentKey类。

这里是指向复合标识1-N关系的DataNucleus文档的链接。可能有助于您确定问题所在。首先，您没有在Child上定义IdClass

---

以下是OpenJPA使用其反向映射工具创建的内容，它似乎工作正常

@Entity
@Table(name="PARENT")
@IdClass(ParentId.class)
public class Parent {
  @OneToMany(targetEntity=Child.class, mappedBy="parent", cascade=CascadeType.MERGE)
  private Set childs = new HashSet();

  @Id
  @Column(length=4)
  private String code;

  @Id
  private int id;

  //omitted getters, setters
}

public class ParentId implements Serializable {
  public String code;
  public int id;

  //omitted getters, setters, toString, equals, hashcode
}

@Entity
@Table(name="CHILD")
@IdClass(ChildId.class)
public class Child {
  @Id
  @Column(length=4)
  private String code;

  @Id
  private int id;

  @Id
  private int index;

  @ManyToOne(fetch=FetchType.LAZY, cascade=CascadeType.MERGE)
  @JoinColumns({@JoinColumn(name="code"), @JoinColumn(name="id")})
  private Parent parent;

  //omitted getters, setters
}

public class ChildId implements Serializable {
  public String code;
  public int id;
  public int index;

  //omitted getters, setters, toString, equals, hashcode
}

另见

---

（将@Id添加到@manytone字段）

我第一次忘记将@IdClass添加到我的示例中，但现在已经更正了。感谢您的链接，但它没有包含外键的主键示例。我需要一个更复杂的例子来表示上面例子中给出的关系。是的。Address.PK将帐户作为其PK的一部分。您的ChildKey不正确您是正确的；我读的时候没有看到。我最终使用了OpenJPA的反向映射工具，它为我提供了解决方案。谢谢你的帮助。

@Entity
@Table(name="PARENT")
@IdClass(ParentId.class)
public class Parent {
  @OneToMany(targetEntity=Child.class, mappedBy="parent", cascade=CascadeType.MERGE)
  private Set childs = new HashSet();

  @Id
  @Column(length=4)
  private String code;

  @Id
  private int id;

  //omitted getters, setters
}

public class ParentId implements Serializable {
  public String code;
  public int id;

  //omitted getters, setters, toString, equals, hashcode
}

@Entity
@Table(name="CHILD")
@IdClass(ChildId.class)
public class Child {
  @Id
  @Column(length=4)
  private String code;

  @Id
  private int id;

  @Id
  private int index;

  @ManyToOne(fetch=FetchType.LAZY, cascade=CascadeType.MERGE)
  @JoinColumns({@JoinColumn(name="code"), @JoinColumn(name="id")})
  private Parent parent;

  //omitted getters, setters
}

public class ChildId implements Serializable {
  public String code;
  public int id;
  public int index;

  //omitted getters, setters, toString, equals, hashcode
}