Question

我一直在尝试将两个不同的表中的数据提取到JPA中的单个实体，但没有结果。

保存来自两个不同表的数据的实体如下：

@Data @Entity @JsonSnakeCase

public class WareHouse {

  @Id
  @GeneratedValue
  private long id;

  @Column(unique = true)
  private String fcId;

  @Enumerated(EnumType.STRING)
  private FCStatus status;

  @OneToMany(cascade = CascadeType.PERSIST, fetch = FetchType.EAGER, mappedBy = "fcId")
  private List<WorkingHours> workingHours;

  @Enumerated(EnumType.STRING)
  private IntegrationType integrationType;
}

另一个实体WorkingHours是：

@Data
@Entity
@JsonSnakeCase
public class WorkingHours {
    @Id
    @GeneratedValue
    private long id;

    private String fcId;
    private LocalDate date;
    private DateTime start;
    private DateTime end;
}

表WareHouse和WorkingHours具有一对多关系，fcId是连接它们的列。

在我的用例中，我必须在上面定义的单个实体WareHouse中获取WorkingHours个详细信息及其WareHouse。我如何实现这一目标？

命名查询（下方）仅提取WareHouse数据，WorkingHours显示为空。数据模型错了吗？或者查询错了？（我认为JPA会在给出注释OneToMany和FetchType等时自动从相关表中获取。）

<named-query name="searchByFcId">
        <query>
            <![CDATA[
            select f from WareHouse f where f.fcId = :fc_id
            ]]>
        </query>
    </named-query>

Answer 1

您可以尝试以下映射。 JPA 2.0规范说明（11.1.21）注意到：

If the referencedColumnName element is missing, the foreign key is assumed to 
refer to the primary key of the referenced table.

然而，它还要注意：

Support for referenced columns that are not primary key columns of the 
referenced table is optional. Applications that use such mappings 
will not be portable.

因此，这是否有效取决于您的提供者。

仓库：

@Data 
@Entity 
@JsonSnakeCase
public class WareHouse {

  @Id
  @GeneratedValue
  private long id;

  @Column(unique = true)
  private String fcId;

  @Enumerated(EnumType.STRING)
  private FCStatus status;

  @OneToMany(mappedBy = "warehouse", cascade = CascadeType.PERSIST, fetch = FetchType.EAGER)
  private List<WorkingHours> workingHours;

  @Enumerated(EnumType.STRING)
  private IntegrationType integrationType;
}

WorkingHours：

@Data
@Entity
@JsonSnakeCase
public class WorkingHours {

    @Id
    @GeneratedValue
    private long id;

    @ManyToOne
    @JoinColumn(name = "fcId", referencedColumnName="fcid")
    private Warehouse warehouse;

    private LocalDate date;
    private DateTime start;
    private DateTime end;
}

JPA从多个表获取到具有命名查询的单个POJO

1 个答案: