48. 응답 DTO - DTO로 바로 받기v7

1. 쿼리 작성하

select * from board_tb where id = 4; 

select count(id) from reply_tb where board_id = 4;

select id, title, content, 4 reply_count from board_tb;

select id, title, content, user_id, 4 reply_count from board_tb bt;

select id, title, content, user_id, (select count(id) from reply_tb where board_id = bt.id) reply_count from board_tb bt;

package shop.mtcoding.blog.board;

import lombok.AllArgsConstructor;
import lombok.Data;
import shop.mtcoding.blog.reply.Reply;
import shop.mtcoding.blog.user.User;

import java.util.ArrayList;
import java.util.List;

public class BoardResponse {

    @AllArgsConstructor
    @Data
    public static class CountDTO {
        private Integer id;
        private String title;
        private String content;
        private Integer userId;
        private Long replyCount;
    }
}

package shop.mtcoding.blog.board;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.query.Param;

import java.util.List;
import java.util.Optional;

public interface BoardJPARepository extends JpaRepository<Board, Integer> {

    @Query("select new shop.mtcoding.blog.board.BoardResponse$CountDTO" +
            "(b.id, b.title, b.content, b.user.id, " +
            "(select count(r.id) from Reply r where r.board.id = b.id)) from Board b")
    List<BoardResponse.CountDTO> findAllWithReplyCount();

    @Query("select b from Board b join fetch b.user u where b.id = :id")
    Optional<Board> findByIdJoinUser(@Param("id") int id);
}

package shop.mtcoding.blog.Board;

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.orm.jpa.DataJpaTest;
import org.springframework.data.domain.Sort;
import shop.mtcoding.blog.board.Board;
import shop.mtcoding.blog.board.BoardJPARepository;
import shop.mtcoding.blog.board.BoardResponse;
import shop.mtcoding.blog.user.User;

import java.util.List;
import java.util.Optional;

@DataJpaTest
public class BoardJPARepositoryTest {

    @Autowired
    private BoardJPARepository boardJPARepository;

    @Test
    public void findAllWithReplyCount_test(){
        // given

        // when
        List<BoardResponse.CountDTO> boardCountDTOList = boardJPARepository.findAllWithReplyCount();
        System.out.println(boardCountDTOList);
        // then
    }
}

[BoardCountDTO(id=1, title=제목1, content=내용1, userId=1, replyCount=0), 
BoardCountDTO(id=2, title=제목2, content=내용2, userId=1, replyCount=0), 
BoardCountDTO(id=3, title=제목3, content=내용3, userId=2, replyCount=1), 
BoardCountDTO(id=4, title=제목4, content=내용4, userId=3, replyCount=3)]