feat : 게시글 좋아요, 좋아요 해제 구현 및 테스트코드 작성 (#31)

* refactor : Post 좋아요 삽입 기능 구현, 동시성 이슈 해결을 위한 낙관적 Lock도입.

* refactor : Post 좋아요 삽입 기능에 대한 테스트 코드 작성

* fix : 엔드포인트 및 메소드명 수정

* feat : Post 좋아요 해제 기능 구현

* fix : 게시물 좋아요 기능 관련 api수정

BE/school/src/main/java/thisisus/school/common/exception/ExceptionCode.java

@@ -22,6 +22,8 @@ public enum ExceptionCode {
   INCORRECT_TOKEN(UNAUTHORIZED, "올바르지 않는 토큰입니다."),
   ALREADY_REGISTERED_EMAIL(CONFLICT, "이미 등록된 이메일입니다."),
   NOT_FOUND_POST(NOT_FOUND, "게시물을 찾을 수 없습니다."),
+  ALREADY_EXIST_POSTLIKE(CONFLICT, "이미 좋아요를 누른 게시물입니다."),
+  NOT_EXIST_POSTLIKE(NOT_FOUND,"해당 게시물에 좋아요 기록이 없습니다."),
   NOT_CORRECT_USER(UNAUTHORIZED, "작성자가 일치하지 않습니다."),
   PUBLIC_KEY_GENERATION_FAILED(INTERNAL_SERVER_ERROR ,"공개 키 생성에 실패했습니다.");
   ;

BE/school/src/main/java/thisisus/school/post/controller/PostLikeController.java

@@ -0,0 +1,29 @@
+package thisisus.school.post.controller;
+
+import lombok.RequiredArgsConstructor;
+import org.springframework.web.bind.annotation.*;
+import thisisus.school.auth.config.AuthenticatedMemberId;
+import thisisus.school.common.response.SuccessResonse;
+import thisisus.school.post.service.PostLikeService;
+
+@RestController
+@RequiredArgsConstructor
+@RequestMapping("/api/post")
+public class PostLikeController {
+
+    private final PostLikeService postLikeService;
+
+    @PostMapping("/{postId}/like")
+    public SuccessResonse likePost(@PathVariable("postId") final Long postId,
+                                   @AuthenticatedMemberId final Long memberId) {
+        postLikeService.likePost(postId, memberId);
+        return SuccessResonse.of();
+    }
+
+    @DeleteMapping("{postId}/like")
+    public SuccessResonse disLikePost(@PathVariable("postId") final Long postId,
+                                      @AuthenticatedMemberId final Long memberId) {
+        postLikeService.disLikePost(postId, memberId);
+        return SuccessResonse.of();
+    }
+}

BE/school/src/main/java/thisisus/school/post/domain/Post.java

@@ -16,6 +16,7 @@
 import lombok.Builder;
 import lombok.Getter;
 import lombok.NoArgsConstructor;
+import org.hibernate.annotations.ColumnDefault;
 import thisisus.school.common.BaseTimeEntity;
 import thisisus.school.member.domain.Member;
 import thisisus.school.post.exception.NotCorrectUserException;
@@ -26,47 +27,57 @@
 @NoArgsConstructor(access = AccessLevel.PROTECTED)
 @AllArgsConstructor
 public class Post extends BaseTimeEntity {
-	@Id
-	@GeneratedValue(strategy = GenerationType.IDENTITY)
-	@Column(name = "post_id")
-	private Long id;
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    @Column(name = "post_id")
+    private Long id;
 
-	@Column
-	private String title;
+    @Column
+    private String title;
 
-	@Column
-	private String content;
+    @Column
+    private String content;
 
-	@Column
-	@Enumerated(EnumType.STRING)
-	private PostCategory category;
+    @Column
+    @Enumerated(EnumType.STRING)
+    private PostCategory category;
 
-	@Column
-	private int likeCount;
+    @Column
+    @ColumnDefault("0")
+    private Integer likeCount;
 
-	@Column
-	private int viewCount;
+    @Column
+    @ColumnDefault("0")
+    private Integer viewCount;
 
-	@Column
-	private boolean isDelete;
+    @Column
+    private boolean isDelete;
 
-	@ManyToOne(fetch = FetchType.LAZY)
-	@JoinColumn(name = "member_id")
-	private Member member;
+    @ManyToOne(fetch = FetchType.LAZY)
+    @JoinColumn(name = "member_id")
+    private Member member;
 
-	public void delete() {
-		this.isDelete = true;
-	}
+    public void delete() {
+        this.isDelete = true;
+    }
 
-	public void update(String title, String content, PostCategory category) {
-		this.title = title;
-		this.content = content;
-		this.category = category;
-	}
+    public void update(String title, String content, PostCategory category) {
+        this.title = title;
+        this.content = content;
+        this.category = category;
+    }
 
-	public void checkWriter(Post post, Long memberId) {
-		if (post.getMember().getId() != memberId) {
-			throw new NotCorrectUserException();
-		}
-	}
+    public void checkWriter(Post post, Long memberId) {
+        if (post.getMember().getId() != memberId) {
+            throw new NotCorrectUserException();
+        }
+    }
+
+    public void increaseLikeCount() {
+        this.likeCount = getLikeCount() + 1;
+    }
+
+    public void decreaseLikeCount() {
+        this.likeCount = getLikeCount() - 1;
+    }
 }

BE/school/src/main/java/thisisus/school/post/exception/AlreadyExistPostLikeException.java

@@ -0,0 +1,10 @@
+package thisisus.school.post.exception;
+
+import thisisus.school.common.exception.CustomException;
+import thisisus.school.common.exception.ExceptionCode;
+
+public class AlreadyExistPostLikeException extends CustomException {
+    public AlreadyExistPostLikeException() {
+        super(ExceptionCode.ALREADY_EXIST_POSTLIKE);
+    }
+}

BE/school/src/main/java/thisisus/school/post/exception/NotExistPostLikeException.java

@@ -0,0 +1,10 @@
+package thisisus.school.post.exception;
+
+import thisisus.school.common.exception.CustomException;
+import thisisus.school.common.exception.ExceptionCode;
+
+public class NotExistPostLikeException extends CustomException {
+    public NotExistPostLikeException() {
+        super(ExceptionCode.NOT_EXIST_POSTLIKE);
+    }
+}

BE/school/src/main/java/thisisus/school/post/repository/PostLikeRepository.java

@@ -0,0 +1,16 @@
+package thisisus.school.post.repository;
+
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
+import thisisus.school.member.domain.Member;
+import thisisus.school.post.domain.Post;
+import thisisus.school.post.domain.PostLike;
+
+import java.util.Optional;
+
+@Repository
+public interface PostLikeRepository extends JpaRepository<PostLike, Long> {
+    boolean existsByMemberAndPost(Member member, Post post);
+
+    PostLike findByMemberAndPost(Member member, Post post);
+}

BE/school/src/main/java/thisisus/school/post/repository/PostRepository.java

@@ -1,10 +1,16 @@
 package thisisus.school.post.repository;
 
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Lock;
 import thisisus.school.post.domain.Post;
 
+import javax.persistence.LockModeType;
 import java.util.List;
+import java.util.Optional;
 
 public interface PostRepository extends JpaRepository<Post, Long> {
     List<Post> findAllByMemberId(Long memberId);
+
+    @Lock(LockModeType.PESSIMISTIC_WRITE)
+    Optional<Post> findWithLockById(Long id);
 }

BE/school/src/main/java/thisisus/school/post/service/PostLikeService.java

@@ -0,0 +1,6 @@
+package thisisus.school.post.service;
+
+public interface PostLikeService {
+    void likePost(Long postId, Long memberId);
+    void disLikePost(Long postId, Long memberId);
+}

BE/school/src/main/java/thisisus/school/post/service/PostLikeServiceImpl.java

@@ -0,0 +1,59 @@
+package thisisus.school.post.service;
+
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+import thisisus.school.member.domain.Member;
+import thisisus.school.member.exception.NotFoundMemberException;
+import thisisus.school.member.repository.MemberRepository;
+import thisisus.school.post.domain.Post;
+import thisisus.school.post.domain.PostLike;
+import thisisus.school.post.exception.AlreadyExistPostLikeException;
+import thisisus.school.post.exception.NotExistPostLikeException;
+import thisisus.school.post.exception.NotFoundPostException;
+import thisisus.school.post.repository.PostLikeRepository;
+import thisisus.school.post.repository.PostRepository;
+
+@Service
+@RequiredArgsConstructor
+public class PostLikeServiceImpl implements PostLikeService {
+    private final PostLikeRepository postLikeRepository;
+    private final PostRepository postRepository;
+    private final MemberRepository memberRepository;
+
+    @Override
+    @Transactional
+    public void likePost(Long postId, Long memberId) {
+        Member member = memberRepository.findById(memberId)
+                .orElseThrow(NotFoundMemberException::new);
+        Post post = postRepository.findWithLockById(postId)
+                .orElseThrow(NotFoundPostException::new);
+        if (postLikeRepository.existsByMemberAndPost(member, post)) {
+            throw new AlreadyExistPostLikeException();
+        }
+        post.increaseLikeCount();
+
+        PostLike postLike = PostLike.builder()
+                .post(post)
+                .member(member)
+                .build();
+
+        postLikeRepository.save(postLike);
+    }
+
+    @Override
+    @Transactional
+    public void disLikePost(Long postId, Long memberId) {
+        Member member = memberRepository.findById(memberId)
+                .orElseThrow(NotFoundMemberException::new);
+        Post post = postRepository.findWithLockById(postId)
+                .orElseThrow(NotFoundPostException::new);
+        if (!postLikeRepository.existsByMemberAndPost(member, post)) {
+            throw new NotExistPostLikeException();
+        }
+        post.decreaseLikeCount();
+
+        PostLike postLike = postLikeRepository.findByMemberAndPost(member, post);
+        postLikeRepository.delete(postLike);
+    }
+}