테크블로그 게시글 좋아요 기능 개발

src/main/java/com/gdsc_knu/official_homepage/controller/post/PostController.java

@@ -104,7 +104,23 @@ public ResponseEntity<PagingResponse<PostResponse.Main>> searchPosts(@RequestPar
                                                                          @RequestParam(value = "size", defaultValue = "20") int size) {
         return ResponseEntity.ok().body(postService.searchPostList(keyword, page, size));
     }
-
+
+    @PostMapping("/{postId}/like")
+    @Operation(summary = "게시글 좋아요 API", description = "게시글에 좋아요를 누른다. 이미 좋아요를 누른 게시글이면 예외가 발생한다.")
+    public ResponseEntity<Void> likePost(@TokenMember JwtMemberDetail jwtMemberDetail,
+                                         @PathVariable("postId") Long postId) {
+        postService.likePost(jwtMemberDetail.getId(), postId);
+        return ResponseEntity.ok().build();
+    }
+
+    @DeleteMapping("/{postId}/like")
+    @Operation(summary = "게시글 좋아요 취소 API", description = "게시글에 좋아요를 취소한다. 좋아요를 누르지 않은 게시글이면 예외가 발생한다.")
+    public ResponseEntity<Void> unlikePost(@TokenMember JwtMemberDetail jwtMemberDetail,
+                                           @PathVariable("postId") Long postId) {
+        postService.unlikePost(jwtMemberDetail.getId(), postId);
+        return ResponseEntity.ok().build();
+    }
+
     @GetMapping("trending")
     @Operation(summary = "카테고리별 인기글 5개 조회", description = "category가 null이면 전제를 조회한다.")
     public ResponseEntity<List<PostResponse.Main>> getTrendingPosts(

src/main/java/com/gdsc_knu/official_homepage/dto/post/PostResponse.java

@@ -43,7 +43,7 @@ public static Main from(Post post) {
                     .category(post.getCategory().name())
                     .createAt(post.getPublishedAt())
                     .likeCount(post.getLikeCount())
-                    .commentCount(post.getCommentList().size())
+                    .commentCount(post.getCommentCount())
                     .sharedCount(post.getSharedCount())
                     .build();
 
@@ -70,8 +70,9 @@ public static class Detail {
         private int sharedCount;
         private boolean canDelete;
         private boolean canModify;
+        private boolean isLiked;
 
-        public static Detail from(Post post, AccessModel access) {
+        public static Detail from(Post post, AccessModel access, boolean isLiked) {
             int length = Math.min(post.getContent().length(), 20);
             return Detail.builder()
                     .id(post.getId())
@@ -83,10 +84,11 @@ public static Detail from(Post post, AccessModel access) {
                     .authorName(post.getMember().getName())
                     .createAt(post.getPublishedAt())
                     .likeCount(post.getLikeCount())
-                    .commentCount(post.getCommentList().size())
+                    .commentCount(post.getCommentCount())
                     .sharedCount(post.getSharedCount())
                     .canDelete(access.canDelete())
                     .canModify(access.canModify())
+                    .isLiked(isLiked)
                     .build();
 
         }

src/main/java/com/gdsc_knu/official_homepage/entity/post/Post.java

@@ -60,4 +60,20 @@ public void update(PostRequest.Update postRequest) {
     public boolean isSaved() {
         return this.status.equals(PostStatus.SAVED);
     }
+
+    public void addCommentCount() {
+        this.commentCount++;
+    }
+
+    public void subtractCommentCount(int deleteCount) {
+        this.commentCount =- deleteCount;
+    }
+
+    public void addLikeCount() {
+        this.likeCount++;
+    }
+
+    public void subtractLikeCount() {
+        this.likeCount--;
+    }
 }

src/main/java/com/gdsc_knu/official_homepage/entity/post/PostLike.java

@@ -0,0 +1,29 @@
+package com.gdsc_knu.official_homepage.entity.post;
+
+import com.gdsc_knu.official_homepage.entity.Member;
+import jakarta.persistence.*;
+import lombok.*;
+
+@Entity
+@Getter
+@Builder
+@AllArgsConstructor
+@NoArgsConstructor(access = AccessLevel.PROTECTED)
+public class PostLike {
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    @ManyToOne(fetch = FetchType.LAZY)
+    private Post post;
+
+    @ManyToOne(fetch = FetchType.LAZY)
+    private Member member;
+
+    public static PostLike from(Post post, Member member) {
+        return PostLike.builder()
+                .post(post)
+                .member(member)
+                .build();
+    }
+}

src/main/java/com/gdsc_knu/official_homepage/exception/ErrorCode.java

@@ -36,6 +36,8 @@ public enum ErrorCode {
     // Post
     POST_NOT_FOUND(404, HttpStatus.NOT_FOUND, "게시글을 찾을 수 없습니다."),
     POST_FORBIDDEN(403, HttpStatus.FORBIDDEN, "게시글을 수정할 수 있는 권한이 없습니다."),
+    POST_ALREADY_LIKED(409, HttpStatus.CONFLICT, "이미 좋아요를 누른 게시글입니다."),
+    POST_NOT_LIKED(404, HttpStatus.NOT_FOUND, "좋아요를 누르지 않은 게시글입니다."),
 
     // Comment
     COMMENT_NOT_FOUND(404, HttpStatus.NOT_FOUND, "댓글을 찾을 수 없습니다."),

src/main/java/com/gdsc_knu/official_homepage/repository/PostLikeRepository.java

@@ -0,0 +1,10 @@
+package com.gdsc_knu.official_homepage.repository;
+
+import com.gdsc_knu.official_homepage.entity.post.PostLike;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+import java.util.Optional;
+
+public interface PostLikeRepository extends JpaRepository<PostLike, Long> {
+    Optional<PostLike> findByMemberIdAndPostId(Long memberId, Long postId);
+}

src/main/java/com/gdsc_knu/official_homepage/service/post/CommentService.java

@@ -35,6 +35,7 @@ public void createComment(Long memberId, Long postId, CommentRequest.Create requ
         Comment parent = getParentComment(request.getGroupId());
         Comment comment = Comment.from(request.getContent(), member, post, parent);
         commentRepository.save(comment);
+        post.addCommentCount();
     }
 
     private Comment getParentComment(Long parentId) {
@@ -91,6 +92,8 @@ public void deleteComment(Long memberId, Long commentId) {
         if (!comment.getAuthor().getId().equals(memberId)) {
             throw new CustomException(ErrorCode.COMMENT_FORBIDDEN);
         }
+        int deleteCount = 1 + comment.getReplies().size();
         commentRepository.delete(comment);
+        comment.getPost().subtractCommentCount(deleteCount);
     }
 }

src/main/java/com/gdsc_knu/official_homepage/service/post/PostService.java

@@ -26,4 +26,8 @@ public interface PostService {
     PagingResponse<PostResponse.Main> searchPostList(String keyword, int page, int size);
 
     List<PostResponse.Main> getTrendingPosts(Category category, int size);
+
+    void likePost(Long memberId, Long postId);
+
+    void unlikePost(Long memberId, Long postId);
 }

src/main/java/com/gdsc_knu/official_homepage/service/post/PostServiceImpl.java

@@ -7,11 +7,13 @@
 import com.gdsc_knu.official_homepage.entity.Member;
 import com.gdsc_knu.official_homepage.entity.enumeration.Role;
 import com.gdsc_knu.official_homepage.entity.post.Post;
+import com.gdsc_knu.official_homepage.entity.post.PostLike;
 import com.gdsc_knu.official_homepage.entity.post.enumeration.Category;
 import com.gdsc_knu.official_homepage.entity.post.enumeration.PostStatus;
 import com.gdsc_knu.official_homepage.exception.CustomException;
 import com.gdsc_knu.official_homepage.exception.ErrorCode;
 import com.gdsc_knu.official_homepage.repository.MemberRepository;
+import com.gdsc_knu.official_homepage.repository.PostLikeRepository;
 import com.gdsc_knu.official_homepage.repository.PostRepository;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
@@ -31,6 +33,7 @@
 public class PostServiceImpl implements PostService {
     private final PostRepository postRepository;
     private final MemberRepository memberRepository;
+    private final PostLikeRepository postLikeRepository;
 
     /**
      * 게시글 작성, 회원만 작성 가능
@@ -62,7 +65,8 @@ public PostResponse.Detail getPost(Long memberId, Long postId) {
             throw new CustomException(ErrorCode.POST_NOT_FOUND);
         }
         AccessModel access = getPostAccess(memberId, post.getMember().getId());
-        return PostResponse.Detail.from(post, access);
+        boolean isLiked = memberId != 0L && postLikeRepository.findByMemberIdAndPostId(memberId, postId).isPresent();
+        return PostResponse.Detail.from(post, access, isLiked);
     }
 
     /**
@@ -142,6 +146,30 @@ public void deletePost(Long memberId, Long postId) {
         postRepository.delete(post);
     }
 
+    @Override
+    public void likePost(Long memberId, Long postId) {
+        postLikeRepository.findByMemberIdAndPostId(memberId, postId)
+                .ifPresent(postLike -> {
+                    throw new CustomException(ErrorCode.POST_ALREADY_LIKED);
+                });
+        Post post = postRepository.findById(postId)
+                .orElseThrow(() -> new CustomException(ErrorCode.POST_NOT_FOUND));
+        Member member = memberRepository.findById(memberId)
+                .orElseThrow(() -> new CustomException(ErrorCode.USER_NOT_FOUND));
+        postLikeRepository.save(PostLike.from(post, member));
+        post.addLikeCount();
+    }
+
+    @Override
+    public void unlikePost(Long memberId, Long postId) {
+        PostLike postLike = postLikeRepository.findByMemberIdAndPostId(memberId, postId)
+                .orElseThrow(() -> new CustomException(ErrorCode.POST_NOT_LIKED));
+        postLikeRepository.delete(postLike);
+        Post post = postRepository.findById(postId)
+                .orElseThrow(() -> new CustomException(ErrorCode.POST_NOT_FOUND));
+        post.subtractLikeCount();
+    }
+
     @Override
     @Transactional(readOnly = true)
     @Cacheable(value = "trending-post", key = "'Is '+#category", unless="#result.size()<5")