具有一对多映射的 Hibernate FetchMode.JOIN

如何解决具有一对多映射的 Hibernate FetchMode.JOIN

有两个实体 InvoiceHeader 和 InvoiceDetail 如下一对多映射。

发票头

@Entity
@Table(name = "view_invoice_hdr")
@IdClass(InvoiceHdrPK.class)
@Getter
@NoArgsConstructor
@EqualsAndHashCode
public class InvoiceHeader{
  
  ....
  
  @OnetoMany(mappedBy = "invoiceHeader",fetch = FetchType.EAGER)
  @Fetch(value = FetchMode.JOIN)
  private List<InvoiceDetail> items;
} 

InvoiceHdrPK

@Getter
@ToString
@NoArgsConstructor
@AllArgsConstructor
@EqualsAndHashCode
public class InvoiceHdrPK implements Serializable {

    private String invoiceNumber;
    private InvoiceSource invoiceSource;
    private InvoiceType invoiceType;
    private Long companyId;
    private Integer invoiceYear;
}

类似InvoiceDetail

@Entity
@Table(name = "view_inv_dtl")
@IdClass(InvoiceDetailPK.class)
@Getter
@NoArgsConstructor
@EqualsAndHashCode
public class InvoiceDetail{
  
  ....
  
    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumns(value = {
            @JoinColumn(name = "invoice_number",referencedColumnName = "invoice_number",insertable = false,updatable = false),@JoinColumn(name = "invoice_source",referencedColumnName = "invoice_source",@JoinColumn(name = "invoice_type",referencedColumnName = "invoice_type",@JoinColumn(name = "company_id",referencedColumnName = "company_id",@JoinColumn(name = "invoice_year",referencedColumnName = "invoice_year",})
    private InvoiceHeader invoiceHeader;
} 

InvoiceDetailPK

@Getter
@ToString
@NoArgsConstructor
@AllArgsConstructor
@EqualsAndHashCode
public class InvoiceDetailPK implements Serializable {

    private String invoiceNumber;
    private InvoiceSource invoiceSource;
    private InvoiceType invoiceType;
    private BigDecimal rate;
    private Long itemNo;
    private Long companyId;
    private Integer invoiceYear;

}

这两个实体都不是数据库级别的实际表，而是作为视图进行维护。

使用 JPA 我正在尝试使用 findAll(Specification,pageable) 和 FetchMode.JOIN 获取发票以避免 n+ 1 查询问题。

但得到异常

org.hibernate.QueryException: query specified join fetching,but the owner of the fetched association was not present in the select list...

那么我该如何解决这个问题，我错过了什么？

解决方法

也许你使用 Set 而不是 List @OneToMany(mappedBy = "invoiceHeader",fetch = FetchType.EAGER) @Fetch(value = FetchMode.JOIN) 私有集合项 = 新 HashSet();

,

您似乎使用了类似于此 select b from A a join a.b b join fetch a.c 的查询。要点是，您加入了一些关联，这些关联您从未在 select 子句中通过父项引用。