[스프링부트] 29. Persistence Context

UserService

package shop.mtcoding.blog.user;

import lombok.RequiredArgsConstructor;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

@RequiredArgsConstructor
@Service
public class UserService {
    private final UserRepository userRepository;

    @Transactional
    public void 회원가입(UserRequest.JoinDTO joinDTO) {
        User user = joinDTO.toEntity(); // 1. 비영속 객체
        System.out.println("비영속 user : " + user.getId());
        userRepository.save(user);
        // user 객체
        System.out.println("영속/동기화 user : " + user.getId());
    }

    public User 로그인(UserRequest.LoginDTO loginDTO) {
        User user = userRepository.findByUsername(loginDTO.getUsername());
        if (!user.getPassword().equals(loginDTO.getPassword())) {
            throw new RuntimeException("유저네임 혹은 비밀번호가 틀렸습니다");
        }
        return user;
    }
}

UserRepository

package shop.mtcoding.blog.user;

import jakarta.persistence.EntityManager;
import lombok.RequiredArgsConstructor;
import org.springframework.stereotype.Repository;

@RequiredArgsConstructor
@Repository
public class UserRepository {
    private final EntityManager em;

    /*
        1. createNativeQuery -> 기본 쿼리 (근본)
        2. createQuery -> JPA가 제공해주는 객체지향 쿼리
        3. NameQuery -> Query Method는 함수 이름으로 쿼리 생성 - 하지마 !
        4. EntityGraph -> 지금 이해 못 함
     */

    public void save(User user) {
        em.persist(user); // 2. user는 이제 영속 객체
        // 3. user는 데이터베이스와 동기화 됨
    }

    // 객체지향 쿼리
    public User findByUsername(String username) {
        return em.createQuery("select u from User u where u.username = :username", User.class)
                .setParameter(username, username)
                .getSingleResult();
    }
}

UserRequest

package shop.mtcoding.blog.user;

import lombok.Data;

public class UserRequest {

    // insert되는 용도의 DTO에는 toEntity 메소드를 만든다.
    @Data
    public static class JoinDTO {
        private String username;
        private String password;
        private String email;

        public User toEntity() {
            return User.builder()
                    .username(username)
                    .password(password)
                    .email(email)
                    .build();
        }
    }

    @Data
    public static class LoginDTO {
        private String username;
        private String password;
    }
}