JPA 使用命名查询从多个表中获取单个 POJO

Question

我一直在尝试将数据从 2 个不同的表中提取到 JPA 中的单个实体，但没有结果。

从两个不同的表中保存数据的实体如下：

@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;
}

WareHouse 和 WorkingHours 表具有一对多关系，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 WareHouse 详细信息及其 WorkingHours。我如何做到这一点？

命名查询（如下）仅获取WareHouse 数据，而WorkingHours 将变为空。数据模型错了吗？还是查询错误？ （我认为 JPA 在给定注释 OneToMany 和 FetchType 等时会自动从相关表中获取数据。）

<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) 说明：

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

但它还继续指出：

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.

所以这是否有效将取决于您的提供商。

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;
}

工作时间：

@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;
}