개요

김영한님의 Spring Data JPA 수업 요약

프로젝트 생성

• Spring Initializr을 사용하여 web, lombok, h2, data jpa 종속성 설치
• 생성 후 설정에서 build, execution, ... > build tools > gradle > build and run using 과 그 밑의 설정 IntelliJ IDEA로 변경
• lombok 설정
• 설정에서 annotation processors 검색 후 Enable Annotation processing 체크

H2 데이터 베이스 설정

어차피 실습용으로만 쓸테니 간단하게

• https://www.h2database.com/html/main.html 접속 후 설치
• /bin/h2.bat 실행 (다른 환경일 때는 h2.sh)

• 최초 첫 시작하면 JDBC URL 에 jdbc:h2:~/datajpa 입력 (DB 파일 생성)
• 이후부터는 jdbc:h2:tcp://localhost/~/datajpa 입력 하고 접속

Member 기능

application.yml

spring:
  datasource:
    url: jdbc:h2:tcp://localhost/~/datajpa
    username: sa
    password:
    driver-class-name: org.h2.Driver
  jpa:
    hibernate:
      ddl-auto: create
    properties:
      hibernate:
        # show_sql: true
        format_sql: true

logging.level:
  org.hibernate.SQL: debug
# org.hibernate.type: trace

기존 JPA

// Member 엔티티
package study.datajpa.entity;

import lombok.Getter;
import lombok.Setter;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

@Entity
@Getter @Setter
public class Member {

    @Id
    @GeneratedValue
    private Long id;
    private String userName;

		// JPA 엔티티에는 무조건 NoArgs 생성자가 필요함.
    // protected 레벨로 열어놔야지 JPA 기능을 사용하는데 문제가 없음.
    protected Member() {
    }

    public Member(String userName) {
        this.userName = userName;
    }
}

// Member 레포지토리
package study.datajpa.repository;

import org.springframework.stereotype.Repository;
import study.datajpa.entity.Member;

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

@Repository
public class MemberJpaRepository {

    @PersistenceContext
    private EntityManager em;

    public Member save(Member member) {
        em.persist(member);
        return member;
    }

    public Member find(Long id) {
        return em.find(Member.class, id);
    }
}

// 레포지토리 테스트 코드
package study.datajpa.repository;

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import study.datajpa.entity.Member;

import javax.transaction.Transactional;

// assertThat 사용하기 위해서 추가해야함.
import static org.assertj.core.api.Assertions.*;

@Transactional
@SpringBootTest
class MemberJpaRepositoryTest {

    @Autowired MemberJpaRepository memberJpaRepository;

    @Test
    public void testMember() {
        Member member = new Member("memberA");
        Member savedMember = memberJpaRepository.save(member);

        Member findMember = memberJpaRepository.find(savedMember.getId());

        assertThat(findMember.getId()).isEqualTo(member.getId());
        assertThat(findMember.getUserName()).isEqualTo(member.getUserName());
    }
}

No EntityManager with actual transaction available for current thread - cannot reliably process 'persist' call; nested exception is javax.persistence.TransactionRequiredException: No EntityManager with actual transaction available for current thread - cannot reliably process 'persist' call