10장 조인 - 페치조인

1) 페치 조인 미적용

@PersistenceUnit
EntityManagerFactory emf;
@Test
public void fetchJoinNo() throws Exception {
 em.flush();
 em.clear();
 Member findMember = queryFactory
 .selectFrom(member)
 .where(member.username.eq("member1"))
 .fetchOne();
 boolean loaded =
emf.getPersistenceUnitUtil().isLoaded(findMember.getTeam());
 assertThat(loaded).as("페치 조인 미적용").isFalse();
}

2) 페치 조인 적용

@Test
public void fetchJoinUse() throws Exception {
 em.flush();
 em.clear();
 Member findMember = queryFactory
 .selectFrom(member)
 .join(member.team, team).fetchJoin()
 .where(member.username.eq("member1"))
 .fetchOne();
 boolean loaded =
emf.getPersistenceUnitUtil().isLoaded(findMember.getTeam());
 assertThat(loaded).as("페치 조인 적용").isTrue();
}