Feature: 게시글 목록 조회 성능 최적화(#76)

backend/src/main/java/aimo/backend/domains/comment/controller/ParentCommentController.java

@@ -1,7 +1,10 @@
 package aimo.backend.domains.comment.controller;
 
+import java.util.List;
+
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.DeleteMapping;
+import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.PutMapping;
@@ -16,6 +19,7 @@
 import aimo.backend.domains.comment.dto.parameter.UpdateParentCommentParameter;
 import aimo.backend.domains.comment.dto.request.SaveParentCommentRequest;
 import aimo.backend.domains.comment.dto.request.UpdateParentCommentRequest;
+import aimo.backend.domains.comment.dto.response.FindCommentsResponse;
 import aimo.backend.domains.comment.service.ParentCommentService;
 import jakarta.validation.Valid;
 import lombok.RequiredArgsConstructor;
@@ -69,4 +73,13 @@ public ResponseEntity<DataResponse<Void>> deleteParentComment(
 
 		return ResponseEntity.ok(DataResponse.ok());
 	}
+
+	@GetMapping("/{postId}/comments")
+	public ResponseEntity<DataResponse<List<FindCommentsResponse>>> findComments(
+		@PathVariable("postId") Long postId
+	) {
+		Long memberId = MemberLoader.getMemberId();
+
+		return ResponseEntity.ok(DataResponse.from(parentCommentService.findComments(memberId, postId)));
+	}
 }

backend/src/main/java/aimo/backend/domains/comment/dto/response/FindCommentsResponse.java

@@ -0,0 +1,75 @@
+package aimo.backend.domains.comment.dto.response;
+
+import java.time.LocalDateTime;
+import java.util.List;
+
+import aimo.backend.domains.comment.entity.ChildComment;
+import aimo.backend.domains.comment.entity.ParentComment;
+import aimo.backend.domains.member.entity.Member;
+import lombok.AllArgsConstructor;
+import lombok.Data;
+
+@Data
+public class FindCommentsResponse {
+
+	private final Boolean isMine;
+	private final Boolean isLiked;
+	private final Long commentId;
+	private final String content;
+	private final String nickname;
+	private final Integer likesCount;
+	private final LocalDateTime createdAt;
+	private final List<ChildCommentDto> childComments;
+
+	public static FindCommentsResponse of(Member member, ParentComment parentComment) {
+		boolean isMine = parentComment.getMember() == member;
+		boolean isLiked = parentComment.getParentCommentLikes()
+			.stream()
+			.anyMatch(like -> like.getMember() == member);
+		List<ChildCommentDto> childCommentDtos = parentComment.getChildComments()
+			.stream()
+			.map(childComment -> ChildCommentDto.of(member, childComment))
+			.toList();
+
+		return new FindCommentsResponse(
+			isMine,
+			isLiked,
+			parentComment.getId(),
+			parentComment.getContent(),
+			parentComment.getNickname(),
+			parentComment.getLikesCount(),
+			parentComment.getCreatedAt(),
+			childCommentDtos
+		);
+	}
+
+
+	@Data
+	@AllArgsConstructor
+	private static class ChildCommentDto {
+		private final Boolean isMine;
+		private final Boolean isLiked;
+		private final Long childCommentId;
+		private final String content;
+		private final String nickname;
+		private final Integer likesCount;
+		private final LocalDateTime createdAt;
+
+		public static ChildCommentDto of(Member member, ChildComment childComment) {
+			boolean isMine = childComment.getMember() == member;
+			boolean isLiked = childComment.getChildCommentLikes()
+				.stream()
+				.anyMatch(like -> like.getMember() == member);
+
+			return new ChildCommentDto(
+				isMine,
+				isLiked,
+				childComment.getId(),
+				childComment.getContent(),
+				childComment.getNickname(),
+				childComment.getLikesCount(),
+				childComment.getCreatedAt()
+			);
+		}
+	}
+}

backend/src/main/java/aimo/backend/domains/comment/repository/ChildCommentRepository.java

@@ -1,7 +1,5 @@
 package aimo.backend.domains.comment.repository;
 
-import java.util.List;
-
 import org.springframework.data.jpa.repository.JpaRepository;
 
 import aimo.backend.domains.comment.entity.ChildComment;
@@ -10,5 +8,5 @@ public interface ChildCommentRepository extends JpaRepository<ChildComment, Long
 
 	Boolean existsByIdAndMember_Id(Long id, Long memberId);
 
-	List<ChildComment> findByMemberId(Long memberId);
+	Integer countByPost_Id(Long postId);
 }

backend/src/main/java/aimo/backend/domains/comment/repository/ParentCommentRepository.java

@@ -3,6 +3,7 @@
 import java.util.List;
 
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
 
 import aimo.backend.domains.comment.entity.ParentComment;
 
@@ -11,4 +12,11 @@ public interface ParentCommentRepository extends JpaRepository<ParentComment, Lo
 	Boolean existsByIdAndMember_Id(Long id, Long memberId);
 
 	List<ParentComment> findAllByMemberId(Long memberId);
+
+	List<ParentComment>  findAllByPost_Id(Long postId);
+
+	@Query("SELECT DISTINCT p FROM ParentComment p JOIN FETCH p.childComments WHERE p.post.id = :postId")
+	List<ParentComment> findAllByPost_IdWithChildComments(Long postId);
+
+	Integer countByPost_Id(Long postId);
 }

backend/src/main/java/aimo/backend/domains/comment/service/ParentCommentService.java

@@ -2,13 +2,16 @@
 
 import static aimo.backend.common.exception.ErrorCode.*;
 
+import java.util.List;
+
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
 import aimo.backend.common.exception.ApiException;
 import aimo.backend.domains.comment.dto.parameter.DeleteParentCommentParameter;
 import aimo.backend.domains.comment.dto.parameter.SaveParentCommentParameter;
 import aimo.backend.domains.comment.dto.parameter.UpdateParentCommentParameter;
+import aimo.backend.domains.comment.dto.response.FindCommentsResponse;
 import aimo.backend.domains.comment.entity.ParentComment;
 import aimo.backend.domains.comment.repository.ParentCommentRepository;
 import aimo.backend.domains.member.entity.Member;
@@ -97,4 +100,18 @@ public void deleteIfParentCommentIsDeletedAndChildrenIsEmpty(ParentComment paren
 
 		parentCommentRepository.delete(parentComment);
 	}
+
+	public List<FindCommentsResponse> findComments(Long memberId, Long postId) {
+		Member member = memberRepository.findById(memberId)
+			.orElseThrow(() -> ApiException.from(MEMBER_NOT_FOUND));
+
+		// 부모 댓글 fetch join으로 조회
+		List<ParentComment> parentComments = parentCommentRepository.findAllByPost_IdWithChildComments(postId);
+
+		List<FindCommentsResponse> responses = parentComments.stream()
+			.map(parentComment -> FindCommentsResponse.of(member, parentComment))
+			.toList();
+
+		return responses;
+	}
 }

backend/src/main/java/aimo/backend/domains/like/entity/PostLike.java

@@ -1,13 +1,12 @@
 package aimo.backend.domains.like.entity;
 
+import static jakarta.persistence.GenerationType.*;
 import static lombok.AccessLevel.*;
 
-import aimo.backend.domains.member.entity.Member;
-import aimo.backend.domains.post.entity.Post;
+import jakarta.persistence.Column;
 import jakarta.persistence.Entity;
-import jakarta.persistence.FetchType;
-import jakarta.persistence.JoinColumn;
-import jakarta.persistence.ManyToOne;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.Id;
 import jakarta.persistence.Table;
 import jakarta.persistence.UniqueConstraint;
 import lombok.Builder;
@@ -22,19 +21,20 @@
 		@UniqueConstraint(columnNames = {"post_id", "member_id"})
 	})
 @NoArgsConstructor(access = PROTECTED)
-public class PostLike extends Like {
+public class PostLike {
 
-	@ManyToOne(fetch = FetchType.LAZY)
-	@JoinColumn(name = "post_id")
-	private Post post;
+	@Id
+	@GeneratedValue(strategy = IDENTITY)
+	@Column(name = "like_id")
+	private Long id;
 
-	@Builder
-	private PostLike(Post post, Member member) {
-		super(member);
-		this.post = post;
-	}
+	private Long postId;
 
-	public static PostLike from(Member member, Post post) {
-		return PostLike.builder().member(member).post(post).build();
+	private Long memberId;
+
+	@Builder
+	private PostLike (Long postId, Long memberId) {
+		this.postId = postId;
+		this.memberId = memberId;
 	}
 }

backend/src/main/java/aimo/backend/domains/like/repository/PostLikeRepository.java

@@ -6,7 +6,7 @@
 
 public interface PostLikeRepository extends JpaRepository<PostLike, Long> {
 
-	void deleteByMember_IdAndPost_Id(Long id, Long postId);
+	void deleteByMemberIdAndPostId(Long id, Long postId);
 
 	boolean existsByPostIdAndMemberId(Long postId, Long memberId);
 }

backend/src/main/java/aimo/backend/domains/like/service/PostLikeService.java

@@ -9,7 +9,6 @@
 import aimo.backend.domains.like.entity.PostLike;
 import aimo.backend.domains.like.model.LikeType;
 import aimo.backend.domains.like.repository.PostLikeRepository;
-import aimo.backend.domains.member.entity.Member;
 import aimo.backend.domains.member.repository.MemberRepository;
 import aimo.backend.domains.like.dto.parameter.LikePostParameter;
 import aimo.backend.domains.post.entity.Post;
@@ -33,20 +32,44 @@ public void likePost(LikePostParameter parameter) {
 
 		Post post = postRepository.findById(postId)
 			.orElseThrow(() -> ApiException.from(POST_NOT_FOUND));
-		Member member = memberRepository.findById(memberId)
-			.orElseThrow(() -> ApiException.from(MEMBER_NOT_FOUND));
+
+		// 존재 확인
+		validatePostExist(postId);
+		validateMemberExist(memberId);
 
 		if (likeType == LikeType.LIKE) {
 			// 라이크가 존재하면 중복 등록 방지
 			if (postLikeRepository.existsByPostIdAndMemberId(postId, memberId))
 				return;
 
-			PostLike postLike = PostLike.from(member, post);
+			// 라이크 등록
+			PostLike postLike = PostLike.builder()
+				.postId(postId)
+				.memberId(memberId)
+				.build();
 			postLikeRepository.save(postLike);
+
+			// 포스트 라이크 수 증가
+			post.increasePostLikesCount();
 			return ;
 		}
 
 		// 라이크가 이미 존재하면 삭제
-		postLikeRepository.deleteByMember_IdAndPost_Id(member.getId(), postId);
+		postLikeRepository.deleteByMemberIdAndPostId(memberId, postId);
+		post.decreasePostLikesCount();
+	}
+
+	// 글 존재 여부
+	private void validatePostExist(Long postId) {
+		if (!postRepository.existsById(postId)) {
+			throw ApiException.from(POST_NOT_FOUND);
+		}
+	}
+
+	// 멤버 존재 여부
+	private void validateMemberExist(Long memberId) {
+		if (!memberRepository.existsById(memberId)) {
+			throw ApiException.from(MEMBER_NOT_FOUND);
+		}
 	}
 }

backend/src/main/java/aimo/backend/domains/member/entity/AccessToken.java

@@ -1,18 +1,23 @@
 package aimo.backend.domains.member.entity;
 
+import static lombok.AccessLevel.*;
+
 import org.springframework.data.annotation.Id;
 import org.springframework.data.redis.core.RedisHash;
 import org.springframework.data.redis.core.index.Indexed;
 
+import lombok.AllArgsConstructor;
 import lombok.Getter;
+import lombok.NoArgsConstructor;
 import lombok.RequiredArgsConstructor;
 
 @Getter
-@RequiredArgsConstructor
+@NoArgsConstructor(access = PROTECTED)
+@AllArgsConstructor
 @RedisHash(value = "accessToken", timeToLive = 3600)
 public class AccessToken {
 	@Id
-	private final Long memberId;
+	private Long memberId;
 	@Indexed
-	private final String accessToken;
+	private String accessToken;
 }

backend/src/main/java/aimo/backend/domains/member/entity/RefreshToken.java

@@ -1,15 +1,19 @@
 package aimo.backend.domains.member.entity;
 
+import static lombok.AccessLevel.*;
+
 import org.springframework.data.annotation.Id;
 import org.springframework.data.redis.core.RedisHash;
 import org.springframework.data.redis.core.index.Indexed;
 
 import lombok.AllArgsConstructor;
 import lombok.Getter;
+import lombok.NoArgsConstructor;
 import lombok.Setter;
 
 @Getter
 @AllArgsConstructor
+@NoArgsConstructor(access = PROTECTED)
 @RedisHash(value = "refreshToken", timeToLive = 1209600)
 public class RefreshToken {
 

backend/src/main/java/aimo/backend/domains/post/dto/requset/FindCommentedPostsByIdRequest.java

@@ -43,33 +43,4 @@ public static FindCommentedPostsByIdRequest of(
 			commentedAt
 		);
 	}
-
-	public static FindCommentedPostsByIdRequest from(ParentComment parentComment) {
-		Post post = parentComment.getPost();
-
-		final Float plaintiffVotesCount = (float)post.getPlaintiffVotesCount();
-		final Float defendantVotesCount = (float)post.getDefendantVotesCount();
-		final Float votesCount = (float)post.getVotesCount();
-
-		// 투표율 계산
-		float voteRatePlaintiff = 0f;
-		float voteRateDefendant = 0f;
-		if (votesCount != 0) {
-			voteRatePlaintiff = plaintiffVotesCount / votesCount;
-			voteRateDefendant = defendantVotesCount / votesCount;
-		}
-
-		return new FindCommentedPostsByIdRequest(
-			post.getId(),
-			post.getTitle(),
-			post.getPreview(),
-			post.getPostLikesCount(),
-			post.getPostViewsCount(),
-			post.getCommentsCount(),
-			voteRatePlaintiff,
-			voteRateDefendant,
-			post.getCreatedAt(),
-			post.getCreatedAt()
-		);
-	}
 }