querydsl : example test

querydsl/src/main/java/com/example/querydsl/entity/Member.java

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+package com.example.querydsl.entity;
+
+import lombok.*;
+
+import javax.persistence.*;
+
+@Entity
+@Getter @Setter
+@NoArgsConstructor(access = AccessLevel.PROTECTED)
+@ToString(of = {"id", "username", "age"})
+public class Member {
+
+    @Id @GeneratedValue
+    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);
+    }
+}

querydsl/src/main/java/com/example/querydsl/entity/Team.java

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+package com.example.querydsl.entity;
+
+import lombok.*;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.Id;
+import javax.persistence.OneToMany;
+import java.util.ArrayList;
+import java.util.List;
+
+@Entity
+@Getter @Setter
+@NoArgsConstructor(access = AccessLevel.PROTECTED)
+@ToString(of = {"id", "name"})
+public class Team {
+
+    @Id @GeneratedValue
+    private Long id;
+    private String name;
+
+    @OneToMany(mappedBy = "team")
+    private List<Member> members = new ArrayList<>();
+
+    public Team(String name) {
+        this.name = name;
+    }
+}

querydsl/src/test/java/com/example/querydsl/entity/MemberTest.java

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+package com.example.querydsl.entity;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.transaction.annotation.Transactional;
+
+import javax.persistence.EntityManager;
+
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+@SpringBootTest
+@Transactional
+class MemberTest {
+
+    @Autowired
+    EntityManager em;
+
+    @Test
+    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.getTeam() = " + member.getTeam());
+        }
+    }
+
+}