JPA專案的結果為空

我有這些 Postgres 表：

create table deals_new
(
    id                  bigserial primary key,
    slip_id             text,
    deal_type           integer,
    timestamp           timestamp,
    employee_id         bigint
        constraint employee_id_fk
            references common.employees
);

create table twap
(
    id                 bigserial     primary key,
    deal_id            varchar          not null,
    employee_id        bigint
        constraint fk_twap__employee_id
            references common.employees,
    status             integer
);

create table common.employees
(
    id              bigint primary key,
    first_name      varchar(150),
    last_name       varchar(150)
);

物體：

@Entity
@NoArgsConstructor
@EqualsAndHashCode
@Getter
@Setter
@ToString
@Table(name = "deals_new")
public class DealTwap {

    @Id
    @Column(name = "id")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;

    @Column(name = "slip_id")
    private String slipId;
    ...
}

@Entity
@NoArgsConstructor
@Getter
@Setter
@Table(name = "twap")
public class Twap implements Serializable {

    @Id
    @Column(name = "id")
    private long id;

    @Column(name = "deal_id")
    private String dealId;

    @Column(name = "employee_id")
    private Long employeeId;

    @OneToMany(fetch = FetchType.LAZY)
    @JoinColumn(name = "slip_id", referencedColumnName = "deal_id")
    private List<Deal> deals;
}

@Entity
@Table(name = "employees")
@NoArgsConstructor
@AllArgsConstructor
@EqualsAndHashCode
@Builder
@Getter
@Setter
@ToString
public class Employee {
    @Id
    @Column(name = "id")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(name = "last_name")
    private String lastName;

    @Column(name = "first_name")
    private String firstName;

    @ManyToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = "account_id")
    private Account account;
}

！！筆記！！！Employee和之間沒有關系Twap

我創建了這個 JPA 存盤庫：

public interface DealsRepository extends JpaRepository<DealTwap, Long> {

    @Query (value =
            "SELECT e.first_name, e.last_name "  
                    "FROM common.deals_new d "  
                    "JOIN common.employees e ON e.id = d.employee_id "  
                    "LEFT OUTER JOIN common.twap t on "  
                    "        t.deal_id = d.slip_id AND "  
                    "        d.timestamp between '11-11-2010' AND '11-11-2011' AND "  
                    "        d.deal_type in (1, 2) "  
                    "OFFSET :offset "  
                    "LIMIT :limit ",
            nativeQuery = true)
    List<ResultDTO> getHistoryAllPairsSearchParam(@Param("offset") int offset,
                                                      @Param("limit") int limit);
}

如您所見，我使用此介面得到了結果：

public interface ResultDTO {
    String getFirstName();
    String getLastName();
}

List<ResultDTO> list = dealsRepository.getHistoryAllPairsSearchParam(...);

    for (ResultDTO item : list) {
        System.out.println("!!!!!!!!!!!!!!! a "   item.getFirstName());
    }

當我運行代碼時，我得到：

!!!!!!!!!!!!!!! a null
!!!!!!!!!!!!!!! a null
!!!!!!!!!!!!!!! a null
..........

你知道有什么問題嗎？結果，我總是得到空值。當我在 SQL 編輯器中運行這個查詢時，我得到了正確的結果表。

uj5u.com熱心網友回復：

您正在嘗試將本機查詢結果映射到非物體類。如果我沒記錯的話，結果列名應該匹配方法名。您是否嘗試過為這樣的列設定別名？

SELECT e.first_name AS firstName, e.last_name AS lastName

您還閱讀過這個Spring Data JPA 將本機查詢結果映射到非物體 POJO嗎？它看起來與您的情況非常相似。

如果這沒有幫助，看起來谷歌有很多關于如何做到這一點的結果本機查詢結果在 dto。

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