[Spring] @OneToMany 댓글 작성하기

package shop.mtcoding.blog.reply;

import jakarta.persistence.*;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;
import org.hibernate.annotations.CreationTimestamp;
import shop.mtcoding.blog.board.Board;
import shop.mtcoding.blog.user.User;

import java.time.LocalDateTime;

@NoArgsConstructor  // 빈생성자가 필요
@Entity
@Data
@Table(name = "reply_tb")
public class Reply {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id ;

    private String comment;
    //user_id 로 테이블 만들어짐.
    @ManyToOne(fetch = FetchType.LAZY)
    private User user ;

    @ManyToOne(fetch = FetchType.LAZY)
    private Board board ;
    @CreationTimestamp
    private LocalDateTime createdAt;

    @Transient
    private boolean isReplyOwner;

    @Builder
    public Reply(int id, String comment, User user, Board board, LocalDateTime createdAt) {
        this.id = id;
        this.comment = comment;
        this.user = user;
        this.board = board;
        this.createdAt = createdAt;
    }

}

1. View 확인

        <!-- 댓글등록 -->
        <div class="card-body">
            <form action="/reply/save" method="post">
                <input type="hidden" name="boardId" value="{{board.id}}">  // hidden 으로 게시글 id를 받음
                <textarea class="form-control" rows="2" name="comment"></textarea>
                <div class="d-flex justify-content-end">
                    <button type="submit" class="btn btn-outline-primary mt-1">댓글등록</button>
                </div>
            </form>
        </div>

2. DTO 만들기

package shop.mtcoding.blog.reply;

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

public class ReplyRequest {
    @Data
   public static class SaveDTO{
        private Integer boardId ;
        private String comment ;

        public Reply toEntity(User sessionUser, Board board) {
            return Reply.builder()
                    .comment(comment)
                    .board(board)
                    .user(sessionUser)
                    .build();
        }

    }
}

3. 레파지토리, 컨트롤러, 서비스

public interface ReplyJPARepository extends JpaRepository<Reply,Integer> {}

@RequiredArgsConstructor
@Service
public class ReplyService {
    private final ReplyJPARepository replyJPARepository ;
    private final BoardJPARepository boardJPARepository ;

    @Transactional
    public Reply 댓글쓰기(ReplyRequest.SaveDTO requestDTO, User sessionUser) {
        Board  board = boardJPARepository.findById(requestDTO.getBoardId())
                .orElseThrow(() -> new Exception404("없는 게시글에 댓글을 작성할 수 없습니다."));
        Reply reply = requestDTO.toEntity(sessionUser,board);
        replyJPARepository.save(reply);
        return reply ;
    }
  }

import jakarta.servlet.http.HttpSession;
import lombok.RequiredArgsConstructor;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import shop.mtcoding.blog.user.User;

@RequiredArgsConstructor
@Controller
public class ReplyController {
    private final ReplyService replyService ;
    private final HttpSession session;

    @PostMapping("/reply/save")
    public String save(ReplyRequest.SaveDTO requestDTO){
        User sessionUser = (User) session.getAttribute("sessionUser");
         Reply reply = replyService.댓글쓰기(requestDTO,sessionUser);

        return "redirect:/board/"+reply.getBoard().getId() ;
    }
 }