CODEWITHSUNDEEP
javahibernatequerydsl
javaOne
javaOne

Reputation: 1

querydsl how to return dto list?

i use querydsl, hibernate i want select data by Dto in Dto list but not working

here is my code

@Data
@Entity
public class Team {

  @Id
  @GeneratedValue
  private Long id;

  private String name;

  @OneToMany(mappedBy = "team")
  private List<Member> members = new ArrayList<>();
}

@Entity
@Setter
public class Member {

  @Id
  @GeneratedValue
  private Long id;

  private String name;

  @ManyToOne
  @JoinColumn(name = "team_id")
  private Team team;

}

@Setter
public class TeamDto {

  private Long id;

  private String name;

  private List<MemberDto> members = new ArrayList<>();
}


@Setter
public class MemberDto {

  private Long id;

  private String name;
}

test

  @BeforeEach
  void setup() {
    queryFactory = new JPAQueryFactory(em);

    Team team = new Team();
    team.setName("teamA");
    em.persist(team);

    Member member = new Member("memberA");
    member.setTeam(team);
    em.persist(member);

    Member member2 = new Member("memberB");
    member2.setTeam(team);
    em.persist(member2);

    em.flush();
    em.clear();
  }

  @Test
  void t1() {
    TeamDto teamDto = queryFactory
        .select(Projections.fields(
            TeamDto.class,
            team.id,
            team.name,
            Projections.fields(
                MemberDto.class,
                member.id,
                member.name
            ).as("members")
        ))
        .from(team)
        .fetchOne();
    System.out.println("teamDto = " + teamDto);
  }

error log is = java.lang.IllegalArgumentException: com.blog.querydsltest.domain.dto.MemberDto is not compatible with java.util.List

what is problem?? is impossible bring data by List dto?? i try to change Projections.fields to bean, construct, ... but not working how can i do ?

Upvotes: 0

Views: 1534

Answers (1)

Jan-Willem Gmelig Meyling
Jan-Willem Gmelig Meyling

Reputation: 3913

Multi level aggregations are currently not supported by QueryDSL. There are also no concrete plans to support it as of now.

For a DTO solution that can fetch associations with it, I recommend you to have a look at Blaze-Persistence Entity Views. With Entity Views the code for your DTO would look something like the following:

@EntityView(Team.class)
public interface TeamDto {

   @IdMapping public Long getId();
   @Mapping("name") public String getName();
   @Mapping("members") public List<MemberDTO> getMembers();

}

If members is not an association on your TeamEntity, you can map it through a @MappingCorrelated binding.

Disclaimer: I am a contributor for Hibernate, QueryDSL and Blaze-Persistence.

Upvotes: 1

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