JPA QueryDSL 프레임워크 - 3 순수 JPA와 QueryDSL

JPA QueryDSL 프레임워크 - 3 순수 JPA와 QueryDSL

 

 

1. 순수 JPA 리포지토리

@Repository
public class MemberJpaRepository {
    private final EntityManager em;
    private final JPAQueryFactory queryFactory;
    public MemberJpaRepository(EntityManager em) {
        this.em = em;
        this.queryFactory = new JPAQueryFactory(em);
    }
    public void save(Member member) {
        em.persist(member);
    }
    public Optional<Member> findById(Long id) {
        Member findMember = em.find(Member.class, id);
        return Optional.ofNullable(findMember);
    }
    public List<Member> findAll() {
        return em.createQuery("select m from Member m", Member.class)
                .getResultList();
    }
    public List<Member> findByUsername(String username) {
        return em.createQuery("select m from Member m where m.username 
                = :username", Member.class)
                .setParameter("username", username)
                .getResultList();
    }
}

 

 

 

2. Querydsl 사용

순수 JPA 리포지토리 - Querydsl 추가

public List<Member> findAll_Querydsl() {
    return queryFactory
            .selectFrom(member).fetch();
}

public List<Member> findByUsername_Querydsl(String username) {
    return queryFactory
            .selectFrom(member)
            .where(member.username.eq(username))
            .fetch();
}

 

 

 

3. 동적 쿼리와 성능 최적화 조회

 

3 - 1. Builder 사용

 

3 - 1 - 1. MemberTeamDto - 조회 최적화용 DTO 추가

@Data
public class MemberTeamDto {
    private Long memberId;
    private String username;
    private int age;
    private Long teamId;
    private String teamName;
    @QueryProjection
    public MemberTeamDto(Long memberId, String username, int age, Long teamId,
                         String teamName) {
        this.memberId = memberId;
        this.username = username;
        this.age = age;
        this.teamId = teamId;
        this.teamName = teamName;
    }
}

 

참고

@QueryProjection 을 사용하면 해당 DTO가 Querydsl을 의존하게 된다.

이런 의존이 싫으면, 해당 에노테이션을 제거하고,

Projection.bean(), fields(), constructor() 을 사용하면 된다.

 

 

3 - 1 - 2. 회원 검색 조건

 

@Data
public class MemberSearchCondition {
    //회원명, 팀명, 나이(ageGoe, ageLoe)
    private String username;
    private String teamName;
    private Integer ageGoe;
    private Integer ageLoe;
}

 

 

3 - 1 - 3. 동적쿼리 - Builder 사용

Builder를 사용한 예제

//Builder 사용
//회원명, 팀명, 나이(ageGoe, ageLoe)
public List<MemberTeamDto> searchByBuilder(MemberSearchCondition condition) {
    BooleanBuilder builder = new BooleanBuilder();
    if (hasText(condition.getUsername())) {
        builder.and(member.username.eq(condition.getUsername()));
    }
    if (hasText(condition.getTeamName())) {
        builder.and(team.name.eq(condition.getTeamName()));
    }
    if (condition.getAgeGoe() != null) {
        builder.and(member.age.goe(condition.getAgeGoe()));
    }
    if (condition.getAgeLoe() != null) {
        builder.and(member.age.loe(condition.getAgeLoe()));
    }
    return queryFactory
            .select(new QMemberTeamDto(
                    member.id,
                    member.username,
                    member.age,
                    team.id,
                    team.name))
            .from(member)
            .leftJoin(member.team, team)
            .where(builder)
            .fetch();
}

 

 

3 - 2. Where절 파라미터 사용

Where절에 파라미터를 사용한 예제

//회원명, 팀명, 나이(ageGoe, ageLoe)
public List<MemberTeamDto> search(MemberSearchCondition condition) {
    return queryFactory
            .select(new QMemberTeamDto(
                    member.id,
                    member.username,
                    member.age,
                    team.id,
                    team.name))
            .from(member)
            .leftJoin(member.team, team)
            .where(usernameEq(condition.getUsername()),
                    teamNameEq(condition.getTeamName()),
                    ageGoe(condition.getAgeGoe()),
                    ageLoe(condition.getAgeLoe()))
            .fetch();
}
private BooleanExpression usernameEq(String username) {
    return isEmpty(username) ? null : member.username.eq(username);
}
private BooleanExpression teamNameEq(String teamName) {
    return isEmpty(teamName) ? null : team.name.eq(teamName);
}
private BooleanExpression ageGoe(Integer ageGoe) {
    return ageGoe == null ? null : member.age.goe(ageGoe);
}
private BooleanExpression ageLoe(Integer ageLoe) {
    return ageLoe == null ? null : member.age.loe(ageLoe);
}

 

참고

where 절에 파라미터 방식을 사용하면 조건 재사용 가능 

//where 파라미터 방식은 이런식으로 재사용이 가능하다.
public List<Member> findMember(MemberSearchCondition condition) {
    return queryFactory
            .selectFrom(member)
            .leftJoin(member.team, team)
            .where(usernameEq(condition.getUsername()),
                    teamNameEq(condition.getTeamName()),
                    ageGoe(condition.getAgeGoe()),
                    ageLoe(condition.getAgeLoe()))
            .fetch();
}

 

 

 

4. 조회 API 컨트롤러 개발

편리한 데이터 확인을 위해 샘플 데이터를 추가하자.

샘플 데이터 추가가 테스트 케이스 실행에 영향을 주지 않도록 다음과 같이 프로파일을 설정하자

 

4 - 1. 프로파일 설정

src/main/resources/application.yml

spring:
  profiles:
    active: local

 

테스트는 기존 application.yml을 복사해서 다음 경로로 복사하고, 프로파일을 test로 수정하자

src/test/resources/application.yml

spring:
  profiles:
    active: test

이렇게 분리하면 main 소스코드와 테스트 소스 코드 실행시 프로파일을 분리할 수 있다.

 

 

4 - 2. 샘플 데이터 추가

@Profile("local")
@Component
@RequiredArgsConstructor
public class InitMember {
    private final InitMemberService initMemberService;
    @PostConstruct
    public void init() {
        initMemberService.init();
    }
    @Component
    static class InitMemberService {
        @PersistenceContext
        EntityManager em;
        @Transactional
        public void init() {
            Team teamA = new Team("teamA");
            Team teamB = new Team("teamB");
            em.persist(teamA);
            em.persist(teamB);
            for (int i = 0; i < 100; i++) {
                Team selectedTeam = i % 2 == 0 ? teamA : teamB;
                em.persist(new Member("member" + i, i, selectedTeam));
            }
        }
    }
}

 

 

4 - 3. 조회 컨트롤러

@RestController
@RequiredArgsConstructor
public class MemberController {
    private final MemberJpaRepository memberJpaRepository;
    @GetMapping("/v1/members")
    public List<MemberTeamDto> searchMemberV1(MemberSearchCondition condition) {
        return memberJpaRepository.search(condition);
    }
}