[Feat]: 게시글 수정 기능 구현

Author: shihan00321

back/src/main/java/com/back/domain/post/controller/PostController.java

@@ -42,4 +42,12 @@ public ResponseEntity<List<PostResponse>> getPosts() {
     public ResponseEntity<PostResponse> getPost(@PathVariable Long postId) {
         return ResponseEntity.ok(postService.getPost(postId));
     }
+
+    @PutMapping("/{postId}")
+    public ResponseEntity<PostResponse> updatePost(
+            @PathVariable Long postId,
+            @RequestBody @Valid PostRequest request) {
+        Long userId = 1L; // fixme 임시 사용자 ID
+        return ResponseEntity.ok(postService.updatePost(userId, postId, request));
+    }
 }

back/src/main/java/com/back/domain/post/entity/Post.java

@@ -52,4 +52,10 @@ public class Post extends BaseEntity {
     public void assignUser(User user) {
         this.user = user;
     }
+
+    public void updatePost(String title, String content, PostCategory category) {
+        this.title = title;
+        this.content = content;
+        this.category = category;
+    }
 }

back/src/main/java/com/back/domain/post/service/PostService.java

@@ -54,4 +54,18 @@ public List<PostResponse> getPosts() {
 
         return PostMapper.toResponseList(posts);
     }
+
+    @Transactional
+    public PostResponse updatePost(Long userId, Long postId, PostRequest request) {
+        return postRepository.findById(postId)
+                .map(post -> {
+                    if (!post.getUser().getId().equals(userId)) {
+                        throw new ApiException(ErrorCode.UNAUTHORIZED_USER);
+                    }
+                    post.updatePost(request.title(), request.content(), request.category());
+                    Post updatedPost = postRepository.save(post);
+                    return PostMapper.toResponse(updatedPost);
+                })
+                .orElseThrow(() -> new ApiException(ErrorCode.POST_NOT_FOUND));
+    }
 }