Ch01. 프로젝트 환경 설정 - 예제 도메인 모델과 동작확인

엔티티 구조

테이블 구조

Member Entity

@Entity
@Getter
@Setter
@NoArgsConstructor(access = AccessLevel.PROTECTED)
@ToString(of = {"id","username","age"})
public class Member {
    @Id
    @GeneratedValue
    @Column(name = "member_id") //DB테이블에 Member_id로 메핑
    private Long id;
    private String username;
    private int age;

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

    /*
    protected Member(){
        //JPA 표준 스팩에 엔티티는 기본 생성자가 있어야 한다.
        //JPA가 프록시 객체를 사용할 때 해당 생성자를 사용하기 때문에
    }
    */
    public Member(String username) {
        this.username = username;
    }

    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); // 반대편도 바꿔준다.
    }

}

Team Entity

@Entity
@Getter
@Setter
@NoArgsConstructor(access = AccessLevel.PROTECTED)
@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;
    }
}

Test

@SpringBootTest
@Transactional
@Rollback(value = false)
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);

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

        //확인
        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());
        }
    }
}