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[백엔드, 웹 개발] 강의입니다.
Querydsl의 기초부터 실무 활용까지, 한번에 해결해보세요!
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배워요!
Querydsl을 기초부터 실무활용까지 한번에 배울 수 있습니다.
단순한 기능 설명을 넘어 실무활용 노하우를 배울 수 있습니다.
JPA를 사용할 때 동적 쿼리와 복잡한 쿼리 문제를 해결할 수 있습니다.
복잡한 쿼리, 동적 쿼리는 이제 안녕!
Querydsl로 자바 백엔드 기술을 단단하게.
???? 본 강의는 로드맵 과정입니다.
- 본 강의는 자바 백엔드 개발의 실전 코스를 완성하는 마지막 강의입니다. 스프링 부트와 JPA 실무 완전 정복 로드맵을 우선 확인해주세요. (링크)
강좌
https://www.inflearn.com/course/querydsl-실전#
강의자료
https://github.com/braverokmc79/jpa-basic-lecture-file2
소스 :
https://github.com/braverokmc79/jpa-querydsl
[6] 실무 활용 - 순수 JPA와 Querydsl
30.순수 JPA 리포지토리와 Querydsl
강의 :
https://www.inflearn.com/course/lecture?courseSlug=querydsl-실전&unitId=30144&tab=curriculum
1) 순수 JPA 리포지토리와 Querydsl
2) 동적쿼리 Builder 적용
3) 동적쿼리 Where 적용
4) 조회 API 컨트롤러 개발
순수 JPA 리포지토리
package study.querydsl.repository;
import com.querydsl.core.BooleanBuilder;
import com.querydsl.core.types.dsl.BooleanExpression;
import com.querydsl.jpa.impl.JPAQueryFactory;
import org.springframework.stereotype.Repository;
import study.querydsl.dto.MemberSearchCondition;
import study.querydsl.dto.MemberTeamDto;
import study.querydsl.dto.QMemberTeamDto;
import study.querydsl.entity.Member;
import javax.persistence.EntityManager;
import java.util.List;
import java.util.Optional;
import static org.springframework.util.StringUtils.hasText;
import static org.springframework.util.StringUtils.isEmpty;
import static study.querydsl.entity.QMember.member;
import static study.querydsl.entity.QTeam.team;
@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();
}
}
순수 JPA 리포지토리 테스트
ingframework.transaction.annotation.Transactional;
import study.querydsl.dto.MemberSearchCondition;
import study.querydsl.dto.MemberTeamDto;
import study.querydsl.entity.Member;
import study.querydsl.entity.Team;
import javax.persistence.EntityManager;
import java.util.List;
import static org.assertj.core.api.Assertions.assertThat;
@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
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();
}
JPAQueryFactory 스프링 빈 등록 다음과 같이
JPAQueryFactory 를 스프링 빈으로 등록해서 주입받아 사용해도 된다.
@Bean
public JPAQueryFactory queryFactory(EntityManager em) {
return new JPAQueryFactory(em);
}
또는
package study.querydsl;
import com.querydsl.jpa.impl.JPAQueryFactory;
import lombok.RequiredArgsConstructor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import javax.persistence.EntityManager;
@Configuration
@RequiredArgsConstructor
public class AppConfig {
private final EntityManager em;
@Bean
public JPAQueryFactory queryFactory() {
return new JPAQueryFactory(em);
}
}
참고: 동시성 문제는 걱정하지 않아도 된다. 왜냐하면 여기서 스프링이 주입해주는 엔티티 매니저는 실제
동작 시점에 진짜 엔티티 매니저를 찾아주는 프록시용 가짜 엔티티 매니저이다. 이 가짜 엔티티 매니저는
실제 사용 시점에 트랜잭션 단위로 실제 엔티티 매니저(영속성 컨텍스트)를 할당해준다.
> 더 자세한 내용은 자바 ORM 표준 JPA 책 13.1 트랜잭션 범위의 영속성 컨텍스트를 참고하자.
31.동적 쿼리와 성능 최적화 조회 - Builder 사용
강의 :
https://www.inflearn.com/course/lecture?courseSlug=querydsl-실전&unitId=30145&tab=curriculum
Builder를 사용한 예제
MemberTeamDto
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;
}
}
MemberSearchCondition
package study.querydsl.dto;
import lombok.Data;
@Data
public class MemberSearchCondition {
//회원명, 팀명, 나이(ageGoe, ageLoe)
private String username;
private String teamName;
private Integer ageGoe;
private Integer ageLoe;
}
1) Where절에 파라미터를 사용한 예제
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.as("memberId"),
member.username,
member.age,
team.id.as("teamId"),
team.name.as("teamName")
))
.from(member)
.leftJoin(member.team, team)
.where(builder)
.fetch();
}
오류 정정
> 강의 영상에서는 member.id.as("memberId") 라고 적었는데, QMemberTeamDto 는 생성자를 사용하기
때문에 필드 이름을 맞추지 않아도 된다. 따라서 member.id 만 적으면 된다.
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(member3);
em.persist(member4);
MemberSearchCondition condition=new MemberSearchCondition();
condition.setAgeGoe(35);
condition.setAgeLoe(40);
condition.setTeamName("teamB");
List<MemberTeamDto> result = memberJpaRepository.searchByBuilder(condition);
Assertions.assertThat(result).extracting("username").containsExactly("member4");
}
출력 쿼리
/* select
member1.id as memberId,
member1.username,
member1.age,
team.id as teamId,
team.name as teamName
from
Member member1
left join
member1.team as team
where
team.name = ?1
and member1.age >= ?2
and member1.age <= ?3 */ select
member0_.member_id as col_0_0_,
member0_.username as col_1_0_,
member0_.age as col_2_0_,
team1_.team_id as col_3_0_,
team1_.name as col_4_0_
from
member member0_
left outer join
team team1_
on member0_.team_id=team1_.team_id
where
team1_.name=?
and member0_.age>=?
and member0_.age<=?
백기선 강좌 반드시 참조 : ★★★ 38.스프링 데이터 JPA: Projection ★★★
package com.example.demojap3.comment;
import lombok.AccessLevel;
import lombok.AllArgsConstructor;
import lombok.Data;
/**
* 클래스방식 커스텀
*/
@Data
@AllArgsConstructor(access = AccessLevel.PROTECTED)
public class CommentSummary2 {
private String comment;
private int up;
private int down;
public String getVotes(){
return getUp() + " : " +getDown();
}
}
package com.example.demojap3.comment;
import org.springframework.data.jpa.repository.EntityGraph;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Modifying;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.query.Param;
import java.util.List;
import java.util.Optional;
public interface CommentRepository extends JpaRepository<Comment, Long> {
/**
* ==> 다음과 같이 제네릭으로 변경
*/
<T>List<T> findByPost_Id(Long id, Class<T> type);
}
★32.동적 쿼리와 성능 최적화 조회 - Where절 파라미터 사용
강의 :
https://www.inflearn.com/course/lecture?courseSlug=querydsl-실전&unitId=30146&tab=curriculum
public List<MemberTeamDto> search(MemberSearchCondition condition){
return queryFactory
.select(new QMemberTeamDto(
member.id.as("memberId"),
member.username,
member.age,
team.id.as("teamId"),
team.name.as("teamName")
))
.from(member)
.leftJoin(member.team, team)
.where(
usernameEq(condition.getUsername()),
teamNameEq(condition.getTeamName()),
ageGoeEq(condition.getAgeGoe()),
ageLoeEq(condition.getAgeLoe())
)
.fetch();
}
private BooleanExpression usernameEq(String username) {
return hasText(username) ? member.username.eq(username) :null;
}
private BooleanExpression teamNameEq(String teamName) {
return hasText(teamName) ? team.name.eq(teamName) :null;
}
private BooleanExpression ageGoeEq(Integer ageGoe) {
return ageGoe!=null? member.age.goe(ageGoe) : null;
}
private BooleanExpression ageLoeEq(Integer ageLoe) {
return ageLoe!=null? member.age.loe(ageLoe) : null;
}
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();
}
33.조회 API 컨트롤러 개발
강의 :
https://www.inflearn.com/course/lecture?courseSlug=querydsl-실전&unitId=30147&tab=curriculum
편리한 데이터 확인을 위해 샘플 데이터를 추가하자.
샘플 데이터 추가가 테스트 케이스 실행에 영향을 주지 않도록 다음과 같이 프로파일을 설정하자
src/main/resources/application.yml
spring: profiles: active: local
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.
샘플 데이터 추가
package study.querydsl;
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;
import javax.annotation.PostConstruct;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
@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;
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;
import javax.annotation.PostConstruct;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
@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));
}
}
}
}
예제 실행(postman)
http://localhost:8080/v1/members?teamName=teamB&ageGoe=31&ageLoe=35
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