게시글 좋아요 API 구현

src/main/java/com/example/solidconnection/comment/dto/CommentCreateRequest.java

@@ -3,26 +3,15 @@
 import com.example.solidconnection.comment.domain.Comment;
 import com.example.solidconnection.post.domain.Post;
 import com.example.solidconnection.siteuser.domain.SiteUser;
-import jakarta.annotation.Nullable;
 import jakarta.validation.constraints.NotBlank;
 import jakarta.validation.constraints.Size;
-import lombok.Getter;
-
-@Getter
-public class CommentCreateRequest {
-
-    @NotBlank(message = "댓글 내용은 빈 값일 수 없습니다.")
-    @Size(min = 1, max = 255, message = "댓글 내용은 최소 1자 이상, 최대 255자 이하여야 합니다.")
-    String content;
-
-    @Nullable
-    Long parentId;
-
-    public CommentCreateRequest(String content, @Nullable Long parentId) {
-        this.content = content;
-        this.parentId = parentId;
-    }
 
+public record CommentCreateRequest(
+        @NotBlank(message = "댓글 내용은 빈 값일 수 없습니다.")
+        @Size(min = 1, max = 255, message = "댓글 내용은 최소 1자 이상, 최대 255자 이하여야 합니다.")
+        String content,
+        Long parentId
+) {
     public Comment toEntity(SiteUser siteUser, Post post, Comment parentComment) {
 
         Comment comment = new Comment(

src/main/java/com/example/solidconnection/comment/service/CommentService.java

@@ -57,9 +57,10 @@ public CommentCreateResponse createComment(String email, Long postId, CommentCre
         SiteUser siteUser = siteUserRepository.getByEmail(email);
         Post post = postRepository.getById(postId);
 
-        Comment parentComment = Optional.ofNullable(commentCreateRequest.getParentId())
-                .map(commentRepository::getById)
-                .orElse(null);
+        Comment parentComment = null;
+        if (commentCreateRequest.parentId() != null) {
+            parentComment = commentRepository.getById(commentCreateRequest.parentId());
+        }
         Comment createdComment = commentRepository.save(commentCreateRequest.toEntity(siteUser, post, parentComment));
 
         return CommentCreateResponse.from(createdComment);

src/main/java/com/example/solidconnection/custom/exception/ErrorCode.java

@@ -61,6 +61,8 @@ public enum ErrorCode {
     INVALID_COMMENT_ID(HttpStatus.BAD_REQUEST.value(), "존재하지 않는 댓글입니다."),
     INVALID_COMMENT_ACCESS(HttpStatus.BAD_REQUEST.value(), "자신의 댓글만 제어할 수 있습니다."),
     CAN_NOT_UPDATE_DEPRECATED_COMMENT(HttpStatus.BAD_REQUEST.value(),"이미 삭제된 댓글을 수정할 수 없습니다."),
+    INVALID_POST_LIKE(HttpStatus.BAD_REQUEST.value(), "존재하지 않는 게시글 좋아요입니다."),
+    DUPLICATE_POST_LIKE(HttpStatus.BAD_REQUEST.value(), "이미 좋아요한 게시글입니다."),
 
     // general
     JSON_PARSING_FAILED(HttpStatus.BAD_REQUEST.value(), "JSON 파싱을 할 수 없습니다."),

src/main/java/com/example/solidconnection/post/controller/PostController.java

@@ -77,4 +77,26 @@ public ResponseEntity<?> deletePostById(
         PostDeleteResponse postDeleteResponse = postService.deletePostById(principal.getName(), code, postId);
         return ResponseEntity.ok().body(postDeleteResponse);
     }
+
+    @PostMapping(value = "/{code}/posts/{post_id}/like")
+    public ResponseEntity<?> likePost(
+            Principal principal,
+            @PathVariable("code") String code,
+            @PathVariable("post_id") Long postId
+    ) {
+
+        PostLikeResponse postLikeResponse = postService.likePost(principal.getName(), code, postId);
+        return ResponseEntity.ok().body(postLikeResponse);
+    }
+
+    @DeleteMapping(value = "/{code}/posts/{post_id}/like")
+    public ResponseEntity<?> dislikePost(
+            Principal principal,
+            @PathVariable("code") String code,
+            @PathVariable("post_id") Long postId
+    ) {
+
+        PostDislikeResponse postDislikeResponse = postService.dislikePost(principal.getName(), code, postId);
+        return ResponseEntity.ok().body(postDislikeResponse);
+    }
 }

src/main/java/com/example/solidconnection/post/domain/Post.java

@@ -4,7 +4,6 @@
 import com.example.solidconnection.comment.domain.Comment;
 import com.example.solidconnection.entity.PostImage;
 import com.example.solidconnection.entity.common.BaseEntity;
-import com.example.solidconnection.entity.mapping.PostLike;
 import com.example.solidconnection.post.dto.PostUpdateRequest;
 import com.example.solidconnection.siteuser.domain.SiteUser;
 import com.example.solidconnection.type.PostCategory;

src/main/java/com/example/solidconnection/post/domain/PostLike.java

@@ -0,0 +1,53 @@
+package com.example.solidconnection.post.domain;
+
+import com.example.solidconnection.siteuser.domain.SiteUser;
+import jakarta.persistence.*;
+import lombok.EqualsAndHashCode;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+@Entity
+@Getter
+@NoArgsConstructor
+@EqualsAndHashCode(of = "id")
+public class PostLike {
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    @ManyToOne(fetch = FetchType.LAZY)
+    @JoinColumn(name = "post_id")
+    private Post post;
+
+    @ManyToOne(fetch = FetchType.LAZY)
+    @JoinColumn(name = "site_user_id")
+    private SiteUser siteUser;
+
+    public void setPostAndSiteUser(Post post, SiteUser siteUser) {
+
+        if (this.post != null) {
+            this.post.getPostLikeList().remove(this);
+        }
+        this.post = post;
+        post.getPostLikeList().add(this);
+
+        if (this.siteUser != null) {
+            this.siteUser.getPostLikeList().remove(this);
+        }
+        this.siteUser = siteUser;
+        siteUser.getPostLikeList().add(this);
+    }
+
+    public void resetPostAndSiteUser() {
+
+        if (this.post != null) {
+            this.post.getPostLikeList().remove(this);
+        }
+        this.post = null;
+
+        if (this.siteUser != null) {
+            this.siteUser.getPostLikeList().remove(this);
+        }
+        this.siteUser = null;
+    }
+}

src/main/java/com/example/solidconnection/post/dto/PostDislikeResponse.java

@@ -0,0 +1,15 @@
+package com.example.solidconnection.post.dto;
+
+import com.example.solidconnection.post.domain.Post;
+
+public record PostDislikeResponse(
+        Long likeCount,
+        Boolean isLiked
+) {
+    public static PostDislikeResponse from(Post post) {
+        return new PostDislikeResponse(
+                post.getLikeCount(),
+                false
+        );
+    }
+}

src/main/java/com/example/solidconnection/post/dto/PostFindResponse.java

@@ -19,6 +19,7 @@ public record PostFindResponse(
         Integer commentCount,
         String postCategory,
         Boolean isOwner,
+        Boolean isLiked,
         LocalDateTime createdAt,
         LocalDateTime updatedAt,
         PostFindBoardResponse postFindBoardResponse,
@@ -27,7 +28,7 @@ public record PostFindResponse(
         List<PostFindPostImageResponse> postFindPostImageResponses
 ) {
 
-    public static PostFindResponse from(Post post, Boolean isOwner, PostFindBoardResponse postFindBoardResponse,
+    public static PostFindResponse from(Post post, Boolean isOwner, Boolean isLiked, PostFindBoardResponse postFindBoardResponse,
                                         PostFindSiteUserResponse postFindSiteUserResponse,
                                         List<PostFindCommentResponse> postFindCommentResponses,
                                         List<PostFindPostImageResponse> postFindPostImageResponses
@@ -42,6 +43,7 @@ public static PostFindResponse from(Post post, Boolean isOwner, PostFindBoardRes
                 postFindCommentResponses.size(),
                 String.valueOf(post.getCategory()),
                 isOwner,
+                isLiked,
                 post.getCreatedAt(),
                 post.getUpdatedAt(),
                 postFindBoardResponse,

src/main/java/com/example/solidconnection/post/dto/PostLikeResponse.java

@@ -0,0 +1,17 @@
+package com.example.solidconnection.post.dto;
+
+import com.example.solidconnection.post.domain.Post;
+
+public record PostLikeResponse(
+        Long likeCount,
+        Boolean isLiked
+
+
+) {
+    public static PostLikeResponse from(Post post) {
+        return new PostLikeResponse(
+                post.getLikeCount(),
+                true
+        );
+    }
+}

src/main/java/com/example/solidconnection/post/repository/PostLikeRepository.java

@@ -0,0 +1,23 @@
+package com.example.solidconnection.post.repository;
+
+import com.example.solidconnection.custom.exception.CustomException;
+import com.example.solidconnection.post.domain.PostLike;
+import com.example.solidconnection.post.domain.Post;
+import com.example.solidconnection.siteuser.domain.SiteUser;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
+
+import java.util.Optional;
+
+import static com.example.solidconnection.custom.exception.ErrorCode.INVALID_POST_LIKE;
+
+@Repository
+public interface PostLikeRepository extends JpaRepository<PostLike, Long> {
+
+    Optional<PostLike> findPostLikeByPostAndSiteUser(Post post, SiteUser siteUser);
+
+    default PostLike getByPostAndSiteUser(Post post, SiteUser siteUser) {
+        return findPostLikeByPostAndSiteUser(post, siteUser)
+                .orElseThrow(() -> new CustomException(INVALID_POST_LIKE));
+    }
+}

src/main/java/com/example/solidconnection/post/repository/PostRepository.java

@@ -4,6 +4,9 @@
 import com.example.solidconnection.post.domain.Post;
 import org.springframework.data.jpa.repository.EntityGraph;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Modifying;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
 import org.springframework.stereotype.Repository;
 
 import java.util.Optional;
@@ -25,4 +28,14 @@ default Post getById(Long id) {
         return findById(id)
                 .orElseThrow(() -> new CustomException(INVALID_POST_ID));
     }
+
+    @Modifying(clearAutomatically = true, flushAutomatically = true)
+    @Query("UPDATE Post p SET p.likeCount = p.likeCount - 1 " +
+            "WHERE p.id = :postId AND p.likeCount > 0")
+    void decreaseLikeCount(@Param("postId") Long postId);
+
+    @Modifying(clearAutomatically = true, flushAutomatically = true)
+    @Query("UPDATE Post p SET p.likeCount = p.likeCount + 1 " +
+            "WHERE p.id = :postId")
+    void increaseLikeCount(@Param("postId") Long postId);
 }

src/main/java/com/example/solidconnection/post/service/PostService.java

@@ -8,6 +8,8 @@
 import com.example.solidconnection.dto.*;
 import com.example.solidconnection.board.domain.Board;
 import com.example.solidconnection.entity.PostImage;
+import com.example.solidconnection.post.domain.PostLike;
+import com.example.solidconnection.post.repository.PostLikeRepository;
 import com.example.solidconnection.post.domain.Post;
 import com.example.solidconnection.post.dto.*;
 import com.example.solidconnection.post.repository.PostRepository;
@@ -24,6 +26,7 @@
 import lombok.RequiredArgsConstructor;
 import org.apache.commons.lang3.EnumUtils;
 import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Isolation;
 import org.springframework.transaction.annotation.Transactional;
 import org.springframework.web.multipart.MultipartFile;
 
@@ -41,6 +44,7 @@ public class PostService {
     private final CommentService commentService;
     private final RedisService redisService;
     private final RedisUtils redisUtils;
+    private final PostLikeRepository postLikeRepository;
 
     private String validateCode(String code) {
         try {
@@ -71,8 +75,8 @@ private void validateQuestion(Post post) {
         }
     }
 
-    private void validatePostCategory(String category){
-        if(!EnumUtils.isValidEnum(PostCategory.class, category)){
+    private void validatePostCategory(String category) {
+        if (!EnumUtils.isValidEnum(PostCategory.class, category) || category.equals(PostCategory.전체.toString())) {
             throw new CustomException(INVALID_POST_CATEGORY);
         }
     }
@@ -81,6 +85,11 @@ private Boolean getIsOwner(Post post, String email) {
         return post.getSiteUser().getEmail().equals(email);
     }
 
+    private Boolean getIsLiked(Post post, SiteUser siteUser) {
+        return postLikeRepository.findPostLikeByPostAndSiteUser(post, siteUser)
+                .isPresent();
+    }
+
     @Transactional
     public PostCreateResponse createPost(String email, String code, PostCreateRequest postCreateRequest,
                                          List<MultipartFile> imageFile) {
@@ -146,20 +155,22 @@ public PostFindResponse findPostById(String email, String code, Long postId) {
         String boardCode = validateCode(code);
 
         Post post = postRepository.getByIdUsingEntityGraph(postId);
+        SiteUser siteUser = siteUserRepository.getByEmail(email);
         Boolean isOwner = getIsOwner(post, email);
+        Boolean isLiked = getIsLiked(post, siteUser);
 
         PostFindBoardResponse boardPostFindResultDTO = PostFindBoardResponse.from(post.getBoard());
         PostFindSiteUserResponse siteUserPostFindResultDTO = PostFindSiteUserResponse.from(post.getSiteUser());
         List<PostFindPostImageResponse> postImageFindResultDTOList = PostFindPostImageResponse.from(post.getPostImageList());
         List<PostFindCommentResponse> commentFindResultDTOList = commentService.findCommentsByPostId(email, postId);
 
         // caching && 어뷰징 방지
-        if (redisService.isPresent(redisUtils.getValidatePostViewCountRedisKey(email,postId))) {
+        if (redisService.isPresent(redisUtils.getValidatePostViewCountRedisKey(email, postId))) {
             redisService.increaseViewCount(redisUtils.getPostViewCountRedisKey(postId));
         }
 
         return PostFindResponse.from(
-                post, isOwner, boardPostFindResultDTO, siteUserPostFindResultDTO, commentFindResultDTOList, postImageFindResultDTOList);
+                post, isOwner, isLiked, boardPostFindResultDTO, siteUserPostFindResultDTO, commentFindResultDTOList, postImageFindResultDTOList);
     }
 
     @Transactional
@@ -178,4 +189,41 @@ public PostDeleteResponse deletePostById(String email, String code, Long postId)
 
         return new PostDeleteResponse(postId);
     }
+
+    @Transactional(isolation = Isolation.READ_COMMITTED)
+    public PostLikeResponse likePost(String email, String code, Long postId) {
+
+        String boardCode = validateCode(code);
+        Post post = postRepository.getById(postId);
+        SiteUser siteUser = siteUserRepository.getByEmail(email);
+        validateDuplicatePostLike(post, siteUser);
+
+        PostLike postLike = new PostLike();
+        postLike.setPostAndSiteUser(post, siteUser);
+        postLikeRepository.save(postLike);
+        postRepository.increaseLikeCount(post.getId());
+
+        return PostLikeResponse.from(postRepository.getById(postId)); // 실시간성을 위한 재조회
+    }
+
+    private void validateDuplicatePostLike(Post post, SiteUser siteUser) {
+        if (postLikeRepository.findPostLikeByPostAndSiteUser(post, siteUser).isPresent()) {
+            throw new CustomException(DUPLICATE_POST_LIKE);
+        }
+    }
+
+    @Transactional(isolation = Isolation.READ_COMMITTED)
+    public PostDislikeResponse dislikePost(String email, String code, Long postId) {
+
+        String boardCode = validateCode(code);
+        Post post = postRepository.getById(postId);
+        SiteUser siteUser = siteUserRepository.getByEmail(email);
+
+        PostLike postLike = postLikeRepository.getByPostAndSiteUser(post, siteUser);
+        postLike.resetPostAndSiteUser();
+        postLikeRepository.deleteById(postLike.getId());
+        postRepository.decreaseLikeCount(post.getId());
+
+        return PostDislikeResponse.from(postRepository.getById(postId)); // 실시간성을 위한 재조회
+    }
 }