Portfolio


public interface UserRepository extedns JpaRepository<User, Long>{
}


//getOne() -> lazy fetch
@Test
@Transactional // 이걸 안붙여주면 아래 에러가 나게 됨. session 이 없다는 에러.
// could not initialize proxy [com.example.bookmanager.domain.User#3] - no Session
// 붙여 주어야 session 유지가 됨
void crud(){
    User user = userRepository.getOne(3L);
    System.out.println(user);
}

//getOne() 구현 부분. em.getReference()를 통해 참조값을 가져오고 실제 값이 필요할때 세션을 통해 조회 
@Override
	public T getOne(ID id) {

		Assert.notNull(id, ID_MUST_NOT_BE_NULL);
		return em.getReference(getDomainClass(), id);
	}


//findById 는 eager fetch
@Test
void crud(){
    User user = userRepository.findById(3L).orElse(null);
    System.out.println(user);
}

//findByID() 구현 -> em.find()
@Override
	public Optional<T> findById(ID id) {

		Assert.notNull(id, ID_MUST_NOT_BE_NULL);

		Class<T> domainType = getDomainClass();

		if (metadata == null) {
			return Optional.ofNullable(em.find(domainType, id));
		}

		LockModeType type = metadata.getLockModeType();

		Map<String, Object> hints = new HashMap<>();
		getQueryHints().withFetchGraphs(em).forEach(hints::put);

		return Optional.ofNullable(type == null ? em.find(domainType, id, hints) : em.find(domainType, id, type, hints));
	}


@Test
    void crud(){
        ExampleMatcher matcher = ExampleMatcher.matching()
                .withIgnorePaths("name")
                .withMatcher("email", endsWith());
        Example<User> example = Example.of(new User("ma", "fastcampus.com"), matcher);
        userRepository.findAll(example).forEach(System.out::println);
    }
// 생성된 쿼리
select
    user0_.id as id1_0_,
    user0_.created_at as created_2_0_,
    user0_.email as email3_0_,
    user0_.name as name4_0_,
    user0_.updated_at as updated_5_0_ 
from
    user user0_ 
where
    user0_.email like ? escape ?

JPA 기본요소

Repository Interface

Repository

getOne() ↔ findById() 의 차이

deleteAll() ↔ deleteAllInBatch()

Like 검색 (ExampleMatcher) → queryDSL를 결국 쓰게됨

Exception Translation

Consistent Exception Hierarchy