将复合外键映射到复合主键

Question

我在jpa/Hibernate中映射复合键时遇到了问题。父实体和子实体都具有复合主键。

@Embeddable
public class PriceRequestLegKey implements Serializable {
   @Column(name = "leg_request_id")
   private String requestId;
   @Column(name = "display_index")
   private int displayIndex;
   ...
}

@Embeddable
public class AllocationKey implements Serializable {

   @Column(name = "leg_request_id")
   private String requestId;
   @Column(name = "display_index")
   private int displayIndex;
   @Column(name = "allocation_index")
   private int allocationIndex;
   ...
}

@Entity(name = "PriceRequestLeg")
public class PriceRequestLegModel {

   @EmbeddedId
   private PriceRequestLegKey legKey;
   @OneToMany(cascade = CascadeType.ALL)
   @JoinColumns({
      @JoinColumn(name = "leg_request_id", referencedColumnName = "leg_request_id"),
      @JoinColumn(name = "display_index", referencedColumnName = "display_index")
   })
   private List<AllocationModel> allocations;
   ...
}

@Entity(name = "Allocation")
public class AllocationModel {

   @EmbeddedId
   private AllocationKey allocationKey;
   @ManyToOne
   @MapsId
   @JoinColumns({
      @JoinColumn(name = "leg_request_id", referencedColumnName = "leg_request_id"),
      @JoinColumn(name = "display_index", referencedColumnName = "display_index")
   })
   private PriceRequestLegModel leg;
   ...
}

在运行时保存它时会出现以下异常：

org.springframework.orm.jpa.JpaSystemException: could not get a field value by reflection getter of com.lbg.legato.rfq.data.entity.AllocationKey.displayIndex; nested exception is org.hibernate.PropertyAccessException: could not get a field value by reflection getter of com.lbg.legato.rfq.data.entity.AllocationKey.displayIndex

我认为这是虚假的，因为有getter和setter。如果在priceRequestLegModel上使用mappedby=“leg”，在allocationModel上使用@mapsid，也会出现同样的错误。有人能指出我在这里做错了什么吗？

Answer 1

您应该将mappedby=“leg”还原为priceRequestlegModel@onetomany注释：

@Entity(name = "PriceRequestLeg")
public class PriceRequestLegModel {

   @EmbeddedId
   private PriceRequestLegKey legKey;
   @OneToMany(mappedBy="leg", cascade = CascadeType.ALL)
   private List<AllocationModel> allocations;
   ...
}

然后应该将AllocationKey更改为引用PriceRequestLegKey:

@Embeddable
public class AllocationKey implements Serializable {

   PriceRequestLegKey legKey; // corresponds to PK type of PriceRequestLegModel
   @Column(name = "allocation_index")
   private int allocationIndex;
   ...
}

然后适当地设置allocation.leg@mapsid注释的值：

@Entity(name = "Allocation")
public class AllocationModel {

   @EmbeddedId
   private AllocationKey allocationKey;
   @ManyToOne
   @MapsId("legKey")
   @JoinColumns({
      @JoinColumn(name = "leg_request_id", referencedColumnName = "leg_request_id"),
      @JoinColumn(name = "display_index", referencedColumnName = "display_index")
   })
   private PriceRequestLegModel leg;
   ...
}

JPA2.2规范第2.4.1节中有一些类似的示例。