[Querydsl] 5. 실무 활용 - 순수 JPA와 Querydsl

📌 순수 JPA 리포지토리와 Querydsl

⚡ 순수 JPA 리포지토리

package study.querydsl.repository;

import com.querydsl.jpa.impl.JPAQueryFactory;
import jakarta.persistence.EntityManager;
import org.springframework.stereotype.Repository;
import study.querydsl.entity.Member;
import study.querydsl.entity.QMember;

import java.util.List;
import java.util.Optional;

import static study.querydsl.entity.QMember.member;

@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();
    }

}

 

순수 JPA 리포지토리 테스트

package study.querydsl.repository;

import jakarta.persistence.EntityManager;
import org.assertj.core.api.Assertions;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.transaction.annotation.Transactional;
import study.querydsl.entity.Member;

import java.util.List;

import static org.assertj.core.api.Assertions.*;
import static org.junit.jupiter.api.Assertions.*;

@SpringBootTest
@Transactional
class MemberJpaRepositoryTest {

    @Autowired
    EntityManager em;

    @Autowired
    MemberJpaRepository memberJpaRepository;

    @Test
    public void basicTest(){
        Member member = new Member("member1", 10);
        memberJpaRepository.save(member);

        Member findMember = memberJpaRepository.findById(member.getId()).get();
        assertThat(findMember).isEqualTo(member);

        List<Member> result1 = memberJpaRepository.findAll();
        assertThat(result1).containsExactly(member);

        List<Member> result2 = memberJpaRepository.findByUsername("member1");
        assertThat(result2).containsExactly(member);

    }
}

 

 

⚡ Querydsl 사용

순수 JPA 리포지토리 - Querydsl 추가

 public List<Member> findByUsername(String username){
        return em.createQuery("select m from Member m where m.username = :username", Member.class)
                .setParameter("username", username)
                .getResultList();
    }

    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();
    }

 

Querydsl 테스트

@Test
public void basicQuerydslTest() {
    Member member = new Member("member1", 10);
    memberJpaRepository.save(member);
    Member findMember = memberJpaRepository.findById(member.getId()).get();
    assertThat(findMember).isEqualTo(member);
    List<Member> result1 = memberJpaRepository.findAll_Querydsl();
    assertThat(result1).containsExactly(member);     
    List<Member> result2 = memberJpaRepository.findByUsername_Querydsl("member1");
    assertThat(result2).containsExactly(member);
}

 

⚡ JPAQueryFactory 스프링 빈 등록

 @Bean
 JPAQueryFactory jpaQueryFactory(EntityManager em) {
     return new JPAQueryFactory(em);
 }

 

 

📌 동적 쿼리와 성능 최적화 조회 - Builder 사용

MemberTeamDto - 조회 최적화용 DTO 추가

package study.querydsl.dto;

import com.querydsl.core.annotations.QueryProjection;
import lombok.Data;

@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;
    }
}

 

회원 검색 조건

package study.querydsl.dto;

import lombok.Data;

@Data
public class MemberSearchCondition {

    //회원명, 팀명, 나이(ageGoe, ageLeo)
    private String username;
    private String teamName;
    private Integer ageGoe;
    private Integer ageLoe;
}

 

 

⚡ 동적 쿼리 - Builder 사용

Builder를 사용한 예제

 //Builder 사용
    //회원명, 팀명, 나이(ageGeo, 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();
    }

 

조회 예제 테스트

    @Test
    public void searchTest() {
        Team teamA = new Team("teamA");
        Team teamB = new Team("teamB");
        em.persist(teamA);
        em.persist(teamB);

        Member member1 = new Member("member1", 10, teamA);
        Member member2 = new Member("member2", 20, teamA);
        Member member3 = new Member("member3", 30, teamB);
        Member member4 = new Member("member4", 40, teamB);

        em.persist(member1);
        em.persist(member2);
        em.persist(member3);
        em.persist(member4);

        MemberSearchCondition condition = new MemberSearchCondition();
        condition.setAgeGoe(35);
        condition.setAgeLoe(40);
        condition.setTeamName("teamB");

        List<MemberTeamDto> result = memberJpaRepository.searchByBuilder(condition);

        assertThat(result).extracting("username").containsExactly("member4");
    }

 

 

📌 동적 쿼리와 성능 최적화 조회 - Where 절 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();
    }

 

 

📌 조회 API 컨트롤러 개발

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

 

샘플 데이터 추가

package study.querydsl;

import jakarta.annotation.PostConstruct;
import jakarta.persistence.EntityManager;
import jakarta.persistence.PersistenceContext;
import lombok.RequiredArgsConstructor;
import org.springframework.context.annotation.Profile;
import org.springframework.stereotype.Component;
import org.springframework.transaction.annotation.Transactional;
import study.querydsl.entity.Member;
import study.querydsl.entity.Team;

@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));
            }
        }
    }
}

 

조회 컨트롤러

package study.querydsl.controller;

import lombok.RequiredArgsConstructor;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import study.querydsl.dto.MemberSearchCondition;
import study.querydsl.dto.MemberTeamDto;
import study.querydsl.repository.MemberJpaRepository;

import java.util.List;

@RestController
@RequiredArgsConstructor
public class MemberController {

    private final MemberJpaRepository memberJpaRepository;

    @GetMapping("/v1/members")
    public List<MemberTeamDto> searchMemberV1(MemberSearchCondition condition){
        return memberJpaRepository.search(condition);
    }
}

 

 

 

김영한님의 <실전! Querydsl>을 수강하고 작성한 글입니다

 

 

 

 

 

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