[feat] 댓글 작성 기능 구현#62

src/main/java/com/back/domain/post/comment/controller/CommentController.java

@@ -1,7 +1,16 @@
 package com.back.domain.post.comment.controller;
 
+import com.back.domain.post.comment.dto.request.CommentCreateRequestDto;
+import com.back.domain.post.comment.dto.response.CommentResponseDto;
+import com.back.domain.post.comment.service.CommentService;
+import com.back.global.rsData.RsData;
+import io.swagger.v3.oas.annotations.Operation;
 import io.swagger.v3.oas.annotations.tags.Tag;
+import jakarta.validation.Valid;
 import lombok.RequiredArgsConstructor;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestBody;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RestController;
 
@@ -11,4 +20,21 @@
 @RequiredArgsConstructor
 public class CommentController {
 
+  private final CommentService commentService;
+
+  /**
+   * 댓글 작성 API
+   * @param postId 댓글을 작성할 게시글 ID
+   * @param reqBody 댓글 작성 요청 DTO
+   * @return 작성된 댓글 정보
+   */
+  @PostMapping
+  @Operation(summary = "댓글 작성")
+  public RsData<CommentResponseDto> createComment(
+      @PathVariable Long postId,
+      @Valid @RequestBody CommentCreateRequestDto reqBody
+  ) {
+    return RsData.successOf(commentService.createComment(postId, reqBody)); // code=200, message="success"
+  }
+
 }

src/main/java/com/back/domain/post/comment/dto/request/CommentCreateRequestDto.java

@@ -0,0 +1,10 @@
+package com.back.domain.post.comment.dto.request;
+
+import jakarta.validation.constraints.NotBlank;
+
+public record CommentCreateRequestDto(
+    Long postId,
+    @NotBlank (message = "내용은 필수입니다.")
+    String content
+) {
+}

src/main/java/com/back/domain/post/comment/dto/response/CommentResponseDto.java

@@ -0,0 +1,25 @@
+package com.back.domain.post.comment.dto.response;
+
+import com.back.domain.post.comment.entity.Comment;
+import java.time.LocalDateTime;
+
+public record CommentResponseDto(
+    Long commentId,
+    Long postId,
+    String userNickName,
+    LocalDateTime createdAt,
+    LocalDateTime updatedAt,
+    String content
+) {
+
+  public CommentResponseDto(Comment comment) {
+    this(
+        comment.getId(),
+        comment.getPost().getId(),
+        comment.getUser().getNickname(),
+        comment.getCreatedAt(),
+        comment.getUpdatedAt(),
+        comment.getContent()
+    );
+  }
+}

src/main/java/com/back/domain/post/comment/service/CommentService.java

@@ -1,10 +1,39 @@
 package com.back.domain.post.comment.service;
 
+import com.back.domain.post.comment.dto.request.CommentCreateRequestDto;
+import com.back.domain.post.comment.dto.response.CommentResponseDto;
+import com.back.domain.post.comment.entity.Comment;
+import com.back.domain.post.comment.repository.CommentRepository;
+import com.back.domain.post.post.entity.Post;
+import com.back.domain.post.post.repository.PostRepository;
+import com.back.domain.user.entity.User;
+import com.back.global.rq.Rq;
 import lombok.RequiredArgsConstructor;
 import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
 
 @Service
 @RequiredArgsConstructor
 public class CommentService {
 
+  private final CommentRepository commentRepository;
+  private final PostRepository postRepository;
+  private final Rq rq;
+
+  // 댓글 작성 로직
+  @Transactional
+  public CommentResponseDto createComment(Long postId, CommentCreateRequestDto reqBody) {
+    User user = rq.getActor();
+
+    Post post = postRepository.findById(postId)
+        .orElseThrow(() -> new IllegalArgumentException("게시글이 존재하지 않습니다. id=" + postId));
+
+    Comment comment = Comment.builder()
+        .post(post)
+        .user(user)
+        .content(reqBody.content())
+        .build();
+
+    return new CommentResponseDto(commentRepository.save(comment));
+  }
 }