CODEWITHSUNDEEP
javasqlspringjpa
M.Dietz
M.Dietz

Reputation: 1000

Im getting a conversion type error during a JPA query, whats the best way to converse efficiently?

Im getting the following error:

"No converter found capable of converting from type [org.springframework.data.jpa.repository.query.AbstractJpaQuery$TupleConverter$TupleBackedMap] to type [de.hiqs.project.DTO.ProjectWithoutEmployeeDTO]"

The query which causes the error:

@Query("SELECT project.id, project.name, project.budget, " +
          "project.description, project.isArchived, project.archivedDate, " +
          "project.creationDate, project.customer.name AS customerName " +
          "FROM  Project project")
  List<ProjectWithoutEmployeeDTO> findAllWithoutEmployee();

My entity:

@Data
@Entity
@ToString(exclude = {"employees"})
@JsonInclude(JsonInclude.Include.NON_NULL)
public class Project {

  @Id
  @GeneratedValue(strategy = GenerationType.AUTO)
  private long id;

  @Column(unique = true)
  private String name;

  private Integer budget;

  private String description;

  private Boolean isArchived;

  private LocalDate archivedDate;

  private LocalDate creationDate;

  @NotNull
  @ManyToOne
  private Customer customer;

  @OneToOne(cascade = CascadeType.ALL)
  private DefaultDailyEntrySettings defaultDailyEntrySettings;

  @ManyToMany
  @JoinTable(
          name = "employee_projects",
          joinColumns = @JoinColumn(name = "project_id"),
          inverseJoinColumns = @JoinColumn(name = "employee_id")
  )
  private List<Employee> employees;

The DTO:

@Data
public class ProjectWithoutEmployeeDTO {

  private long id;
  private String name;
  private Integer budget;
  private String description;
  private Boolean isArchived;
  private LocalDate archivedDate;
  private LocalDate creationDate;
  private String customerName;
}

So it seems like he cant convert the query result to ProjectWithoutEmployeeDTO. I thought it would work out automatically because the class has the exact same named attributes as the query result, but it seems like it doesnt. Whats the best way to convert the result efficiently? I could return a list of objects instead of a list of ProjectWithoutEmployeeDTO and convert it manually inside the service, but that doesnt seem like the best way.

Edit: I managed to do it with 

@Query("SELECT new classpath.ProjectWithoutEmployeeDTO(project.id, project.name, project.budget, " +
          "project.description, project.isArchived, project.archivedDate, " +
          "project.creationDate, project.customer.name) " +
          "FROM  Project project")
  List<ProjectWithoutEmployeeDTO> findAllWithoutEmployee();

And then just add that constructor to the DTO or let Lambok do it automatically with @AllArgsConstructor

Upvotes: 0

Views: 241

Answers (1)

Simon Martinelli
Simon Martinelli

Reputation: 36143

Your query should use the constructor expression:

@Query("SELECT NEW yourpackage.ProjectWithoutEmployeeDTO(project.id, project.name, project.budget, " +
       "project.description, project.isArchived, project.archivedDate, " +
       "project.creationDate, project.customer.name AS customerName) " +
       "FROM  Project project")

Please note that ProjectWithoutEmployeeDTO must be the fully qualified

Upvotes: 1

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