1장 JPQL 예제

1)

Member.java

package study.querydsl.entity;

import lombok.*;

import javax.persistence.*;

@Entity
@Getter @Setter
@NoArgsConstructor(access = AccessLevel.PROTECTED)
@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) {
        this(username,0,null);
    }

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


}

Team.java

package study.querydsl.entity;

import lombok.*;

import javax.persistence.*;
import java.util.ArrayList;
import java.util.List;

@Entity
@Getter @Setter
@NoArgsConstructor(access = AccessLevel.PROTECTED)
@ToString(of = {"id","name"})
public class Team {

    @Id
    @GeneratedValue
    @JoinColumn(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;
    }
}

MemberTest.java

package study.querydsl.entity;


import org.junit.jupiter.api.Test;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.annotation.Commit;
import org.springframework.transaction.annotation.Transactional;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

import java.util.List;

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

@SpringBootTest
@Transactional
@Commit
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("members=" + members);
            System.out.println("-> member.team=" + member.getTeam());
        }
    }


}