Query DSL 시작하기

• 참고
  • Querydsl 기본문법 학습하기
  • Querydsl 다이나믹 쿼리 사용하기JPA와 비교
• JPA 비교해 JPA의 장점
  • 가독성이 좋다.
    • JPA에서 기본적으로 제공하는 기능을 넘어서는 기능은 일반적으로 native query 옵션으로 수행한다. -> 문자열을 이어붙이는 형태이므로 오타로 인해 런타임 시 오류가 발생할 가능성이 높다.
  • 컴파일 시점에서 에러를 체크할 수 있다.
  • IDE의 자동 완성 기능이 지원된다.
  • 동적쿼리를 지원한다.
• 단점
  • 추가적인 학습이 필요하다.
    • ex) member.age.gt(10)은 age > 10을 의미한다.
  • native query문이 아니므로, RDBMS나 MySQL에서 쿼리문을 실행하기 위해서는 다시 쿼리문을 작성해야 한다.

주의 사항
jpa에서 사용되는 Entity 등의 어노테이션이 javax -> jakarta로 패키지가 이동하여 아래의 예제 실행 시 'javax/persistence/entity' 에러를 발생할 수 있다.
해결 방법 : 아래의 예제의 dependency에 아래의 annotationProcessor를 추하면된다.

annotationProcessor "com.querydsl:querydsl-apt:${queryDslVersion}:jakarta"

spring boot 3.0.0 이상은 다음 글 참고

2022.12.12 - [Spring/Querydsl] - [Spring boot 3.0.0 이상] gradle.build 설정

[Spring boot 3.0.0 이상] gradle.build 설정

Depdency

buildscript {
    ext {
        queryDslVersion = "5.0.0"
    }
}

plugins {
    id 'org.springframework.boot' version '2.7.0'
    id 'io.spring.dependency-management' version '1.0.11.RELEASE'
    id 'java'

    // querydsl 추가
    id "com.ewerk.gradle.plugins.querydsl" version "1.0.10"
}

group = 'walter.unit'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = '11'

configurations {
    compileOnly {
        extendsFrom annotationProcessor
    }
}

repositories {
    mavenCentral()
}

dependencies {
    implementation 'org.springframework.boot:spring-boot-starter-data-jpa'
    implementation 'org.springframework.boot:spring-boot-starter-mustache'
    implementation 'org.springframework.boot:spring-boot-starter-web'
    runtimeOnly 'mysql:mysql-connector-java'

    // querydsl 추가
    implementation "com.querydsl:querydsl-jpa:${queryDslVersion}"
    implementation "com.querydsl:querydsl-apt:${queryDslVersion}"

    compileOnly 'org.projectlombok:lombok'
    annotationProcessor 'org.projectlombok:lombok'
    testImplementation 'org.springframework.boot:spring-boot-starter-test'
}

tasks.named('test') {
    useJUnitPlatform()
}

// querydsl 추가 시작
def querydslDir = "$buildDir/generated/querydsl"

querydsl {
    jpa = true
    querydslSourcesDir = querydslDir
}

sourceSets {
    main.java.srcDir querydslDir
}

configurations {
    querydsl.extendsFrom compileClasspath
}

compileQuerydsl{
    options.annotationProcessorPath = configurations.querydsl
}

compileQuerydsl.doFirst {    if(file(querydslDir).exists() )        delete(file(querydslDir))}

yml

spring:
  datasource:
    url: jdbc:mysql://localhost:3306/test?allowPublicKeyRetrieval=true&useSSL=false&useUnicode=true&serverTimezone=Asia/Seoul&zeroDateTimeBehavior=convertToNull
    username: username
    password: password
    driver-class-name: com.mysql.cj.jdbc.Driver

  jpa:
    database-platform: org.hibernate.dialect.MySQL8Dialect
    hibernate:
      ddl-auto: none #배포시 NONE으로 변경

Entity 추가

@Entity
@Getter
@NoArgsConstructor
@AllArgsConstructor
@Builder
public class Member {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(name = "name")
    private String name;

    @Column(name = "age")
    private int age;

    @Column(name = "address")
    private String address;


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

}

==================

@Entity
@Getter
@NoArgsConstructor
@AllArgsConstructor
@Builder
public class Team {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String name;

    private String type;

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "team")
    private List<Member> memberList;
}

QModel 생성

• gradle - tasks - build - clean
• gradle - tasks - other - compileQuerydsl
• build - generated 파일에서 QModel 확인

/**
 * QMember is a Querydsl query type for Member
 */
@Generated("com.querydsl.codegen.DefaultEntitySerializer")
public class QMember extends EntityPathBase<Member> {

    private static final long serialVersionUID = 851117285L;

    private static final PathInits INITS = PathInits.DIRECT2;

    public static final QMember member = new QMember("member1");

    public final StringPath address = createString("address");

    public final NumberPath<Integer> age = createNumber("age", Integer.class);

    public final NumberPath<Long> id = createNumber("id", Long.class);

    public final StringPath name = createString("name");

    public final QTeam team;

    public QMember(String variable) {
        this(Member.class, forVariable(variable), INITS);
    }

    public QMember(Path<? extends Member> path) {
        this(path.getType(), path.getMetadata(), PathInits.getFor(path.getMetadata(), INITS));
    }

    public QMember(PathMetadata metadata) {
        this(metadata, PathInits.getFor(metadata, INITS));
    }

    public QMember(PathMetadata metadata, PathInits inits) {
        this(Member.class, metadata, inits);
    }

    public QMember(Class<? extends Member> type, PathMetadata metadata, PathInits inits) {
        super(type, metadata, inits);
        this.team = inits.isInitialized("team") ? new QTeam(forProperty("team")) : null;
    }

}

=======================

/**
 * QTeam is a Querydsl query type for Team
 */
@Generated("com.querydsl.codegen.DefaultEntitySerializer")
public class QTeam extends EntityPathBase<Team> {

    private static final long serialVersionUID = -955329688L;

    public static final QTeam team = new QTeam("team");

    public final NumberPath<Long> id = createNumber("id", Long.class);

    public final ListPath<Member, QMember> memberList = this.<Member, QMember>createList("memberList", Member.class, QMember.class, PathInits.DIRECT2);

    public final StringPath name = createString("name");

    public final StringPath type = createString("type");

    public QTeam(String variable) {
        super(Team.class, forVariable(variable));
    }

    public QTeam(Path<? extends Team> path) {
        super(path.getType(), path.getMetadata());
    }

    public QTeam(PathMetadata metadata) {
        super(Team.class, metadata);
    }

}

Config

@Configuration  
public class QuerydslConfiguration {

@PersistenceContext  
private EntityManager entityManager;

@Bean  
public JPAQueryFactory jpaQueryFactory(){  
return new JPAQueryFactory(entityManager);  
}

}

RepositorySupport

@Repository  
public class MemberRepositorySupport extends QuerydslRepositorySupport {

private final JPAQueryFactory queryFactory;

public MemberRepositorySupport(JPAQueryFactory queryFactory) {  
super(Member.class);  
this.queryFactory = queryFactory;  
}

public List findByName(String name){  
return queryFactory  
.selectFrom(member)  
.where(member.name.eq(name))  
.fetch();  
}

}

\==================

@Repository  
public class TeamRepositorySupport extends QuerydslRepositorySupport {

private final JPAQueryFactory queryFactory;

public TeamRepositorySupport(JPAQueryFactory queryFactory) {  
super(Team.class);  
this.queryFactory = queryFactory;  
}

}

DB

member table

team table

 

Test

@SpringBootTest  
class MemberRepositorySupportTest {

@Autowired  
private MemberRepositorySupport memberRepositorySupport;

@Test  
void getTest1(){  
Member test1 = memberRepositorySupport.findByNameOne("test1");

StringBuilder sb = new StringBuilder();  
sb.append("id: ");  
sb.append(test1.getId());  
sb.append(" / ");  
sb.append("age: ");  
sb.append(test1.getAge());  
sb.append(" / ");  
sb.append("address: ");  
sb.append(test1.getAddress());  
sb.append(" / ");  
sb.append("teamType : ");  
sb.append(test1.getTeam().getType());  
sb.append(" / ");  
sb.append("teamName : ");  
sb.append(test1.getTeam().getName());

System.out.println(sb.toString());

}

}

\================ 결과  
id: 1 / age: 10 / address: null / teamType : amature / teamName : team1

쿠팡으로 연결 클릭

제주삼다수 그린

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