refactor: 사용자가 좋아요 눌렀는지 여부를 확인 하는 영역에서 N+1문제 해결

Author: Curry4182

lime-domain/src/main/java/com/programmers/lime/domains/feed/implementation/FeedCursorReader.java

@@ -1,6 +1,8 @@
 package com.programmers.lime.domains.feed.implementation;
 
 import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
 
 import org.springframework.stereotype.Component;
 
@@ -10,6 +12,7 @@
 import com.programmers.lime.common.model.Hobby;
 import com.programmers.lime.domains.feed.model.FeedCursorSummary;
 import com.programmers.lime.domains.feed.model.FeedCursorSummaryLike;
+import com.programmers.lime.domains.feed.model.FeedLikeInfo;
 import com.programmers.lime.domains.feed.model.FeedSortCondition;
 import com.programmers.lime.domains.feed.repository.FeedLikeRepository;
 import com.programmers.lime.domains.feed.repository.FeedRepository;
@@ -26,8 +29,6 @@ public class FeedCursorReader {
 
 	private final FeedRepository feedRepository;
 	private final MemberReader memberReader;
-	private final FeedLikeRepository feedLikeRepository;
-	private final FeedReader feedReader;
 
 	public CursorSummary<FeedCursorSummaryLike> getFeedByCursor(
 		final Hobby hobby,
@@ -47,18 +48,33 @@ public CursorSummary<FeedCursorSummaryLike> getFeedByCursor(
 			pageSize
 		);
 
-		List<FeedCursorSummaryLike> feedCursorSummaryLikes = feedCursorSummaries.stream().map(
-			feedCursorSummary -> {
-				boolean isLike = feedLikeRepository.existsByMemberIdAndFeed(
-					loginMemberId,
-					feedReader.read(feedCursorSummary.feedId())
-				);
+		List<FeedCursorSummaryLike> feedCursorSummaryLikes = getFeedCursorSummaryLikes(
+			loginMemberId,
+			feedCursorSummaries
+		);
+
+		return CursorUtils.getCursorSummaries(feedCursorSummaryLikes);
+	}
+
+	private List<FeedCursorSummaryLike> getFeedCursorSummaryLikes(
+		final Long loginMemberId,
+		final List<FeedCursorSummary> feedCursorSummaries
+	) {
+		List<Long> feedIds = feedCursorSummaries.stream()
+			.map(FeedCursorSummary::feedId)
+			.toList();
+
+		Set<Long> feedLikeInfoSet = feedRepository.getFeedLikeInfos(feedIds, loginMemberId)
+			.stream()
+			.map(FeedLikeInfo::feedId)
+			.collect(Collectors.toSet());
 
+		return feedCursorSummaries.stream().map(
+			feedCursorSummary -> {
+				boolean isLike = feedLikeInfoSet.contains(feedCursorSummary.feedId());
 				return feedCursorSummary.of(isLike);
 			}
 		).toList();
-
-		return CursorUtils.getCursorSummaries(feedCursorSummaryLikes);
 	}
 
 	private int getPageSizeByParameter(final CursorPageParameters parameters) {

lime-domain/src/main/java/com/programmers/lime/domains/feed/model/FeedLikeInfo.java

@@ -0,0 +1,8 @@
+package com.programmers.lime.domains.feed.model;
+
+public record FeedLikeInfo(
+	Long feedId,
+	Long memberId
+
+) {
+}

lime-domain/src/main/java/com/programmers/lime/domains/feed/repository/FeedRepositoryForCursor.java

@@ -4,7 +4,7 @@
 
 import com.programmers.lime.common.model.Hobby;
 import com.programmers.lime.domains.feed.model.FeedCursorSummary;
-import com.programmers.lime.domains.feed.model.FeedCursorSummaryLike;
+import com.programmers.lime.domains.feed.model.FeedLikeInfo;
 import com.programmers.lime.domains.feed.model.FeedSortCondition;
 
 public interface FeedRepositoryForCursor {
@@ -15,4 +15,9 @@ List<FeedCursorSummary> findAllByCursor(
 		final String cursorId,
 		final int pageSize
 	);
+
+	List<FeedLikeInfo> getFeedLikeInfos(
+		final List<Long> feedIds,
+		final Long loginMemberId
+	);
 }

lime-domain/src/main/java/com/programmers/lime/domains/feed/repository/FeedRepositoryForCursorImpl.java

@@ -2,6 +2,7 @@
 
 import static com.programmers.lime.domains.feed.domain.QFeed.*;
 import static com.programmers.lime.domains.feed.domain.QFeedItem.*;
+import static com.programmers.lime.domains.feed.domain.QFeedLike.*;
 import static com.programmers.lime.domains.member.domain.QMember.*;
 import static com.querydsl.core.group.GroupBy.*;
 
@@ -12,11 +13,13 @@
 import com.programmers.lime.domains.feed.model.FeedCursorItem;
 import com.programmers.lime.domains.feed.model.FeedCursorSummary;
 import com.programmers.lime.domains.feed.model.FeedCursorSummaryLike;
+import com.programmers.lime.domains.feed.model.FeedLikeInfo;
 import com.programmers.lime.domains.feed.model.FeedSortCondition;
 import com.programmers.lime.domains.member.model.MemberInfo;
 import com.querydsl.core.types.ConstantImpl;
 import com.querydsl.core.types.Order;
 import com.querydsl.core.types.OrderSpecifier;
+import com.querydsl.core.types.Predicate;
 import com.querydsl.core.types.Projections;
 import com.querydsl.core.types.dsl.BooleanExpression;
 import com.querydsl.core.types.dsl.Expressions;
@@ -32,6 +35,15 @@ public class FeedRepositoryForCursorImpl implements FeedRepositoryForCursor {
 
 	private final JPAQueryFactory jpaQueryFactory;
 
+	private static BooleanExpression eqHobby(final Hobby hobby) {
+
+		if (hobby == null) {
+			return null;
+		}
+
+		return feed.hobby.eq(hobby);
+	}
+
 	public List<FeedCursorSummary> findAllByCursor(
 		final Long nicknameMemberId,
 		final Hobby hobby,
@@ -42,7 +54,7 @@ public List<FeedCursorSummary> findAllByCursor(
 		List<Long> feedIds = jpaQueryFactory.select(feed.id)
 			.from(feed)
 			.where(
-				feed.hobby.eq(hobby),
+				eqHobby(hobby),
 				eqMemberId(nicknameMemberId),
 				lessThanNextCursorId(feedSortCondition, cursorId)
 			).orderBy(feedSort(feedSortCondition), feed.id.desc())
@@ -86,6 +98,32 @@ public List<FeedCursorSummary> findAllByCursor(
 			);
 	}
 
+	@Override
+	public List<FeedLikeInfo> getFeedLikeInfos(
+		final List<Long> feedIds,
+		final Long loginMemberId
+	) {
+		return jpaQueryFactory
+			.select(
+				Projections.constructor(
+					FeedLikeInfo.class,
+					feedLike.feed.id,
+					feedLike.memberId
+				)
+			)
+			.from(feedLike)
+			.where(feedLike.feed.id.in(feedIds), eqLoginMemberIdWithFeedLikes(loginMemberId))
+			.fetch();
+	}
+
+	private Predicate eqLoginMemberIdWithFeedLikes(final Long loginMemberId) {
+		if (loginMemberId == null) {
+			return null;
+		}
+
+		return feedLike.memberId.eq(loginMemberId);
+	}
+
 	private BooleanExpression eqMemberId(
 		final Long nicknameMemberId
 	) {