Ch01. 프로젝트 환경 설정 - 예제 도메인 모델과 동작확인

ERD

Member, Team 설계

• 도메인 모델과, ERD
• member - team 이 일대다 관계로 양방향 연관관계를 가지고 있다.

Entity

Member

@Entity
@Getter
@Setter
@NoArgsConstructor(access = AccessLevel.PROTECTED)
@ToString(of = {"id","username","age"}) //양방향 연관관계는 출력 X
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){
        this(username,0);
    }
    public Member(String username,int age){
        this(username,age,null);
    }

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

    private void changeTeam(Team team) { //양방향 연관관계 Set
        this.team = team;
        team.getMembers().add(this);
    }

}

Team

Team

 

@SpringBootTest
@Transactional
class MemberTest {

    @PersistenceContext
    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);

        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());
        }
    }
}

• Team, Member, Test를 작성한다.