예제 도메인과 동작확인

학습 페이지

member

package hello.querydsl.entity;

import jakarta.persistence.*;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;
import lombok.ToString;

@Entity
@Getter @Setter
@NoArgsConstructor
@ToString(of = {"id", "username", "age"})
public class 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, 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);
    }

}

team

package hello.querydsl.entity;

import jakarta.persistence.*;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;
import lombok.ToString;

import java.util.ArrayList;
import java.util.List;

@Entity
@Getter @Setter
@NoArgsConstructor
@ToString(of = {"id", "name"})
public 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;
    }
}

롬복의 toString을 사용할때 그냥 사용하면 순환참조가 된다.

이를 해결하기 위해 위처럼 of={}등으로 필요한 필드만 지정해 오버라이딩할 필드를 지정할 수 있다.

이제 테스트 해보자

엔티티 테스트

package hello.querydsl.entity;

import jakarta.persistence.EntityManager;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import java.util.List;

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

@SpringBootTest
class MemberTest {

    @Autowired
    EntityManager 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);

        //영속성 컨텍스트 초기화(쿼리 확인용)
        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());
        }
    }
}

데이터가 잘 들어가고 있다. 지연로딩도 적용된걸 확인할 수 있음.