Spring，JPA：如何使用多对多关系桥表设置查询另一个实体下的实体

如何解决Spring，JPA：如何使用多对多关系桥表设置查询另一个实体下的实体

我对 Spring 还很陌生。我正在尝试使用此 ERD 查询一位捐赠者下的所有捐赠：

捐助者|----* 协议*----|捐赠（使用桥接表的多对多关系）

这是我的代码：

Donor.java

@Entity
@Data
@AllArgsConstructor
@NoArgsConstructor
public class Donor extends Auditable implements Comparable<Donor>{
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @NotBlank(message = "Cannot have an empty account number field.")
    private String accountNumber;
    private String accountName;
    private String salutation;
    private String donorName;
    private String cellphoneNumber;
    private String emailAddress;
    private String companyTIN;
    private String phone1;
    private String phone2;
    private String faxnumber;
    private String address1;
    private String address2;
    private String address3;
    private String address4;
    private String address5;
    private String companyAddress;
    private LocalDate birthDate;
    private String notes;

    @OnetoMany(mappedBy = "donor")
    List<MOA> moaList = new ArrayList<>();
    ...
}

捐赠.java

@Entity
@Data
@AllArgsConstructor
@NoArgsConstructor
public class Donation extends Auditable implements Comparable<Donation> {
   
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    @NotBlank(message = "Cannot have an empty account number field.")
    private String accountNumber;
    private String accountName;
    private String orNumber;
    private String date;
    private Double amount;
    private String notes;
    private String needCertificate;
    private String purpoSEOfDonation;

    @OnetoMany(mappedBy = "donation")
    List<MOA> moaList = new ArrayList<>();
    ...
}

MOA.java（协议）

@Entity
@Data
@NoArgsConstructor
@AllArgsConstructor
public class MOA extends Auditable{
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;


    @ManyToOne
    @JoinColumn(name = "donor_id")
    @JsonIgnoreProperties("moaList")
    private Donor donor;

    @ManyToOne
    @JoinColumn(name = "donation_id")
    @JsonIgnoreProperties("moaList")
    private Donation donation;

    private String name;
    private String donorAccountNumber;
    private Long foreignDonationId;
    private LocalDate dateSigned;
}

在我的 DonorRepository 中，我试图进行这个查询，我希望它能给我我想要的：

public interface DonorRepository extends JpaRepository<Donor,Long> {
    ...
    @Query(value = "SELECT * FROM donor WHERE account_number = ?1",nativeQuery = true)
    List<Donation> findDonorsDonations(String accountNumber);
    ...

这给了我一个错误

无法从类型 [java.lang.Object[]] 转换为类型 [com.package.server.domain.Donation] 的值 '{1,admin,2021-04-01 10:29:53.0,学校,123456,null,John Doe,Mr.} ';嵌套异常是 org

解决方法

您可以使用规范 api 和 SpecificationExecutor。

您必须加入 Donation with MAO（MAO with Donor）然后查询特定捐赠者的捐赠。