java - JPA 使用命名查询从多个表获取单个 POJO

Question

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

保存两个不同表中数据的实体如下:

@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，我必须在单个实体 WareHouse 中获取 WareHouse 详细信息及其 WorkingHours，如上面所定义。我该如何实现这一目标？

命名查询(如下)仅获取 WareHouse 数据，而 WorkingHours 为空。数据模型是不是错了？或者查询有误？ (我认为当给定注释 OneToMany 和 FetchType 等时，JPA 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.

但是它还指出:

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.

因此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;
}