[Spring] 응답 DTO 만들기

1. 회원 정보 조회 DTO

package shop.mtcoding.blog.user;


import lombok.Data;

public class UserResponse {
    // 엔티티를 dto로. 그래서 응답은 풀생성자가 필요함
    @Data
    public static class DTO{
        private int id ;
        private String username;
        private String email;

        public DTO(User user) {
            this.id = user.getId();
            this.username = user.getUsername();
            this.email = user.getEmail();
        }
    }
}

  public UserResponse.DTO 회원조회(int id){
        User user = userJPARepository.findById(id)
                .orElseThrow(() -> new Exception404("회원정보를 찾을 수 없습니다."));
        return new UserResponse.DTO(user) ;//엔티티 생명 종료, 여기서 레이지 로딩 종료
    }

    @GetMapping("/api/users/{id}")
    public ResponseEntity<?> userinfo(@PathVariable Integer id){
        UserResponse.DTO responseDTO = userService.회원조회(id);
        return ResponseEntity.ok(new ApiUtil(responseDTO));
    }

2. 게시글 목록 조회 DTO

package shop.mtcoding.blog.board;

import lombok.Data;
import shop.mtcoding.blog.user.User;

public class BoardResponse {
    @Data
    public static class MainDTO{
        private int id;
        private String title;

        public MainDTO(Board board) {
            this.id = board.getId();
            this.title = board.getTitle();
        }
    }
    
    }

    public List<BoardResponse.MainDTO> 글목록조회() {
        Sort sort = Sort.by(Sort.Direction.DESC, "id");
        List<Board> boardList = boardJPARepository.findAll(sort);
        
        return boardList.stream().map(board -> new BoardResponse.MainDTO(board)).toList();
    }

    @GetMapping("/")
    public ResponseEntity<?> main(){
        List<BoardResponse.MainDTO> responseDTO = boardService.글목록조회();
        return  ResponseEntity.ok(new ApiUtil(responseDTO));
    }

3. 상세보기 DTO

boardId,
title
content

boarUserId
username

replyId
comment
replyUserId
replyUsername

{
	"id":1,
	"title":"제목1",
	"content":"내용1",
	"user":{
			"id":1,
			"username":"ssar"
			}
		"re 
}

@Data
    public static class DetailDTO{
        private int id;
        private String title;
        private String content ;
        private int userId ;
        private String usernaem;  // 게시글 작성자
        private boolean isOwner ;

        private List<ReplyDTO> replies = new ArrayList<>();     // new 를해서 초기화해야 값이 없을 때 0의 빈 배열을 리턴함. null 이면 터짐

        public DetailDTO(Board board, User sessionUser) {
            this.id = board.getId();
            this.title = board.getTitle();
            this.content = board.getContent();
            this.userId = board.getUser().getId();
            this.usernaem = board.getUser().getUsername();
            
            this.isOwner = false;
            if(sessionUser!=null){
                if(sessionUser.getId()==userId){
                  isOwner =true ;  
                }
            }
            //List 타입을 api 스트림으로 DTO 타입으로 담는다.
            this.replies = board.getReplies().stream().map(reply -> new ReplyDTO(reply,sessionUser)).toList();
        }
        @Data
        public class ReplyDTO{
            private int id ;
            private String content ;
            private int userId ;
            private String username ; // 댓글 작성자
            private boolean isOwner ;


            public ReplyDTO(Reply reply,User sessionUser) {
                this.id = reply.getId();
                this.content = reply.getComment();
                this.userId = reply.getUser().getId();
                this.username = reply.getUser().getUsername(); //lazy loading 발동
                
                this.isOwner = false;
                if(sessionUser!=null){
                    if(sessionUser.getId()==userId){
                        isOwner =true ;
                    }
                }
            }
        }


    

    public BoardResponse.DetailDTO 글상세보기(int boardId, User sessionUser) {
        Board board = boardJPARepository.findByIdJoinUser(boardId)
                .orElseThrow(() -> new Exception404("게시글을 찾을 수 없습니다"));

        return new BoardResponse.DetailDTO(board,sessionUser);
    }

    @GetMapping("/api/boards/{id}/detail")
    public ResponseEntity<?> detail(@PathVariable int id){
        User sessionUser = (User) session.getAttribute("sessionUser");
        BoardResponse.DetailDTO responseDTO = boardService.글상세보기(id,sessionUser);
        return  ResponseEntity.ok(new ApiUtil(responseDTO));
    }

4. 예외 경우

select * from board_tb ;

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

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

public class BoardResponse {

    @AllArgsConstructor
    @Data
    public static class CountDTO {

        private Integer id ;
        private String title ;
        private String content;
        private Integer userId ;
        private Long replyCount ;


    }
}

    @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();    //<> 내부는 원래 Board 타입만 받을 수 잇음
		
		// 클래스 내부에 static 으로 DTO를 만든다면 $ 를 사용해서 클래스$DTO 로 표시해야 한다.

    @Test
    public void findAllWithCount_test(){

        List<BoardResponse.CountDTO> CountDTOList = boardJPARepository.findAllWithReplyCount();

        for(int i=0;i<CountDTOList.size();i++){
            System.out.println(CountDTOList.get(i));
        }

    }