QueryDsl

Querydsl 설정

build.gradle에 querydsl 설정 추가

//querydsl 추가

implementation 'com.querydsl:querydsl-jpa'

//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
}
//querydsl 추가 끝

예제 도메인 모델

//Member 엔티티//

@Entity
@Getter @Setter
@NoArgsConstructor(access = AccessLevel.PROTECTED)
@ToString(of = {"id", "username", "age"})
public classs Member{

    @Id
    @GeneratedValue
    @Column(name = "member_id")
    private Long id;
    private String username;
    private int age;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "team_id")
    private Team team;

    public Member(String username){
        this(username,0);
    }

    public Member(String username, int age){
        thist(username, age, null);
    }

    public Member(String username, int age, Team team){
        this.username = username;
        this.age = age;
        if(team != null){
            changeTeam(team);
        }
    }

    public void changeTeam(Team team){
        this.team = team;
        team.getMembers().add(this);
    }
}
// 실무에선 가급적 @Setter 사용금지//

//Team 엔티티//

@Entity
@Getter@Setter
@NoArgsConstructor(access = AccessLevel.PROTECTED)
@ToString(of={"id","name"})
pulic class team{
    @Id@GeneratedValue
    @Column(name = "team_id")
    private Long id;
    private String name;

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

    public Team(String name){
        this.name = name;
    }
}

//test//

@SpringBootTest
@Transactional
@Commit
public class MemberTest{
    
    @Autowired
    EntityManeger em;

    @Test
    public void testEntity(){

        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);

         //초기화 
         em.flush(); 
         em.clear();

          List<Member> members =
           em.createQuery("select m from Member m",
                 Member.class)
                  .getResultList();
          for (Member member : members) {
              System.out.println("member=" + member);
              System.out.println("-> member.team=" + 
              member.getTeam());
        } 
    }
}