[feat] 특정 책으로 작성된 피드 목록 조회 api 개발

src/main/java/konkuk/thip/book/adapter/out/persistence/BookQueryPersistenceAdapter.java

@@ -30,6 +30,11 @@ public boolean existsSavedBookByUserIdAndBookId(Long userId, Long bookId) {
         return savedBookJpaRepository.existsByUserIdAndBookId(userId, bookId);
     }
 
+    @Override
+    public boolean existsBookByIsbn(String isbn) {
+        return bookJpaRepository.existsByIsbn(isbn);
+    }
+
     @Override
     public List<Book> findSavedBooksByUserId(Long userId) {
         UserJpaEntity user = userJpaRepository.findById(userId)

src/main/java/konkuk/thip/book/adapter/out/persistence/repository/BookJpaRepository.java

@@ -24,4 +24,6 @@ public interface BookJpaRepository extends JpaRepository<BookJpaEntity, Long> {
             "AND r.startDate <= CURRENT_TIMESTAMP " + // 진행 중인 방만 조회 (모집 중 / 만료된 방 x)
             "ORDER BY r.roomPercentage DESC")  // 방의 진행률이 높은 순서로 정렬
     List<BookJpaEntity> findJoiningRoomsBooksByUserId(Long userId);
+
+    boolean existsByIsbn(String isbn);
 }

src/main/java/konkuk/thip/book/application/port/out/BookQueryPort.java

@@ -8,6 +8,8 @@ public interface BookQueryPort {
 
     boolean existsSavedBookByUserIdAndBookId(Long userId, Long bookId);
 
+    boolean existsBookByIsbn(String isbn);
+
     List<Book> findSavedBooksByUserId(Long userId);
 
     List<Book> findJoiningRoomsBooksByUserId(Long userId);

src/main/java/konkuk/thip/feed/adapter/in/web/FeedQueryController.java

@@ -3,6 +3,10 @@
 import io.swagger.v3.oas.annotations.Operation;
 import io.swagger.v3.oas.annotations.Parameter;
 import io.swagger.v3.oas.annotations.tags.Tag;
+import jakarta.validation.constraints.Pattern;
+import konkuk.thip.feed.adapter.in.web.response.FeedRelatedWithBookResponse;
+import konkuk.thip.feed.application.port.in.dto.FeedRelatedWithBookQuery;
+import konkuk.thip.feed.application.port.in.dto.FeedRelatedWithBookSortType;
 import konkuk.thip.common.dto.BaseResponse;
 import konkuk.thip.common.security.annotation.UserId;
 import konkuk.thip.common.swagger.annotation.ExceptionDescription;
@@ -26,6 +30,7 @@ public class FeedQueryController {
     private final FeedShowUserInfoUseCase feedShowUserInfoUseCase;
     private final FeedShowSingleUseCase feedShowSingleUseCase;
     private final FeedShowWriteInfoUseCase feedShowWriteInfoUseCase;
+    private final FeedRelatedWithBookUseCase feedRelatedWithBookUseCase;
 
     @Operation(
             summary = "피드 전체 조회",
@@ -106,4 +111,27 @@ public BaseResponse<FeedShowSingleResponse> showSingleFeed(
     public BaseResponse<FeedShowWriteInfoResponse> showFeedWriteInfo() {
         return BaseResponse.ok(feedShowWriteInfoUseCase.showFeedWriteInfo());
     }
+
+    @GetMapping("/feeds/related-books/{isbn}")
+    @Operation(
+            summary = "특정 책으로 작성된 피드 조회",
+            description = "책의 ISBN을 통해 해당 책과 관련된 피드를 조회합니다."
+    )
+    public BaseResponse<FeedRelatedWithBookResponse> showFeedsByBook(
+            @Parameter(description = "책의 ISBN 번호 (13자리 숫자)", example = "9781234567890")
+            @PathVariable("isbn") @Pattern(regexp = "\\d{13}", message = "ISBN은 13자리 숫자여야 합니다.") final String isbn,
+            @Parameter(description = "정렬 기준 (like: 좋아요순, latest: 최신순) / 기본 : 좋아요 순", example = "like")
+            @RequestParam(required = false, defaultValue = "like") final String sort,
+            @Parameter(description = "커서 (첫번째 요청시 : null, 다음 요청시 : 이전 요청에서 반환받은 nextCursor 값)")
+            @RequestParam(required = false) final String cursor,
+            @Parameter(hidden = true) @UserId final Long userId
+    ) {
+        return BaseResponse.ok(feedRelatedWithBookUseCase.getFeedsByBook(FeedRelatedWithBookQuery.builder()
+                .isbn(isbn)
+                .sortType(FeedRelatedWithBookSortType.from(sort))
+                .cursor(cursor)
+                .userId(userId)
+                .build())
+        );
+    }
 }

src/main/java/konkuk/thip/feed/adapter/in/web/response/FeedRelatedWithBookResponse.java

@@ -0,0 +1,36 @@
+package konkuk.thip.feed.adapter.in.web.response;
+
+import lombok.Builder;
+
+import java.util.List;
+
+@Builder
+public record FeedRelatedWithBookResponse(
+       List<FeedRelatedWithBookDto> feeds,
+       String nextCursor,
+       boolean isLast
+) {
+    public record FeedRelatedWithBookDto(
+            Long feedId,
+            Long creatorId,
+            boolean isWriter,
+            String creatorNickname,
+            String creatorProfileImageUrl,
+            String aliasName,
+            String aliasColor,
+            String postDate,
+            String isbn,
+            String bookTitle,
+            String bookAuthor,
+            String contentBody,
+            String[] contentUrls,
+            int likeCount,
+            int commentCount,
+            boolean isSaved,
+            boolean isLiked
+    ) {}
+
+    public static FeedRelatedWithBookResponse of(List<FeedRelatedWithBookDto> feeds, String nextCursor, boolean isLast) {
+        return new FeedRelatedWithBookResponse(feeds, nextCursor, isLast);
+    }
+}

src/main/java/konkuk/thip/feed/adapter/out/persistence/FeedQueryPersistenceAdapter.java

@@ -103,7 +103,6 @@ public CursorBasedList<FeedQueryDto> findSpecificUserFeedsByCreatedAt(Long feedO
 
     @Override
     public int countAllFeedsByUserId(Long userId) {
-        // int 로 강제 형변환 해도 괜찮죠??
         return (int) feedJpaRepository.countAllFeedsByUserId(userId, StatusType.ACTIVE);
     }
 
@@ -153,4 +152,32 @@ public Set<Long> findSavedFeedIdsByUserIdAndFeedIds(Set<Long> feedIds, Long user
     public List<TagCategoryQueryDto> findAllTags() {
         return feedJpaRepository.findAllTags();
     }
+
+    @Override
+    public CursorBasedList<FeedQueryDto> findFeedsByBookIsbnOrderByLike(String isbn, Long userId, Cursor cursor) {
+        LocalDateTime lastCreatedAt = cursor.isFirstRequest() ? null : cursor.getLocalDateTime(0);
+        Integer lastLikeCount = cursor.isFirstRequest() ? null : cursor.getInteger(1);
+        int size = cursor.getPageSize();
+
+        List<FeedQueryDto> feedQueryDtos = feedJpaRepository.findFeedsByBookIsbnOrderByLikeCount(isbn, userId, lastCreatedAt, lastLikeCount, size);
+
+        return CursorBasedList.of(feedQueryDtos, size, feedQueryDto -> {
+            Cursor nextCursor = new Cursor(List.of(feedQueryDto.createdAt().toString(),
+                    feedQueryDto.likeCount().toString()));
+            return nextCursor.toEncodedString();
+        });
+    }
+
+    @Override
+    public CursorBasedList<FeedQueryDto> findFeedsByBookIsbnOrderByLatest(String isbn, Long userId, Cursor cursor) {
+        LocalDateTime lastCreatedAt = cursor.isFirstRequest() ? null : cursor.getLocalDateTime(0);
+        int size = cursor.getPageSize();
+
+        List<FeedQueryDto> feedQueryDtos = feedJpaRepository.findFeedsByBookIsbnOrderByCreatedAt(isbn, userId, lastCreatedAt, size);
+
+        return CursorBasedList.of(feedQueryDtos, size, feedQueryDto -> {
+            Cursor nextCursor = new Cursor(List.of(feedQueryDto.createdAt().toString()));
+            return nextCursor.toEncodedString();
+        });
+    }
 }

src/main/java/konkuk/thip/feed/adapter/out/persistence/repository/FeedQueryRepository.java

@@ -19,4 +19,8 @@ public interface FeedQueryRepository {
     List<FeedQueryDto> findSpecificUserFeedsByCreatedAt(Long feedOwnerId, LocalDateTime lastCreatedAt, int size);
 
     List<TagCategoryQueryDto> findAllTags();
+
+    List<FeedQueryDto> findFeedsByBookIsbnOrderByLikeCount(String isbn, Long userId, LocalDateTime lastCreatedAt, Integer lastLikeCount, int size);
+
+    List<FeedQueryDto> findFeedsByBookIsbnOrderByCreatedAt(String isbn, Long userId, LocalDateTime lastCreatedAt, int size);
 }

src/main/java/konkuk/thip/feed/adapter/out/persistence/repository/FeedQueryRepositoryImpl.java

@@ -1,17 +1,17 @@
 package konkuk.thip.feed.adapter.out.persistence.repository;
 
 import com.querydsl.core.Tuple;
-import com.querydsl.core.types.dsl.BooleanExpression;
-import com.querydsl.core.types.dsl.CaseBuilder;
-import com.querydsl.core.types.dsl.Expressions;
-import com.querydsl.core.types.dsl.NumberExpression;
+import com.querydsl.core.types.dsl.*;
+import com.querydsl.jpa.JPAExpressions;
 import com.querydsl.jpa.impl.JPAQueryFactory;
+import jakarta.annotation.Nullable;
 import konkuk.thip.book.adapter.out.jpa.QBookJpaEntity;
 import konkuk.thip.common.entity.StatusType;
 import konkuk.thip.feed.adapter.out.jpa.*;
+import konkuk.thip.feed.application.port.out.dto.FeedQueryDto;
+import konkuk.thip.feed.application.port.out.dto.QFeedQueryDto;
 import konkuk.thip.feed.application.port.out.dto.QTagCategoryQueryDto;
 import konkuk.thip.feed.application.port.out.dto.TagCategoryQueryDto;
-import konkuk.thip.feed.application.port.out.dto.FeedQueryDto;
 import konkuk.thip.room.adapter.out.jpa.QCategoryJpaEntity;
 import konkuk.thip.user.adapter.out.jpa.QAliasJpaEntity;
 import konkuk.thip.user.adapter.out.jpa.QFollowingJpaEntity;
@@ -227,7 +227,6 @@ public List<TagCategoryQueryDto> findAllTags() {
                 .orderBy(c.categoryId.asc(), t.tagId.asc()) //Id 순 정렬
                 .fetch();
     }
-
     private List<Long> fetchMyFeedIdsByCreatedAt(Long userId, LocalDateTime lastCreatedAt, int size) {
         return jpaQueryFactory
                 .select(feed.postId)
@@ -283,4 +282,105 @@ private FeedQueryDto toDto(FeedJpaEntity e, Integer priority) {
                 .isPriorityFeed(isPriorityFeed)
                 .build();
     }
+
+    /**
+     * 책 ISBN으로 피드를 조회하고, 좋아요 수 기준으로 정렬하여 페이징 처리
+     */
+    @Override
+    public List<FeedQueryDto> findFeedsByBookIsbnOrderByLikeCount(
+            String isbn,
+            Long userId,
+            @Nullable LocalDateTime lastCreatedAt,
+            @Nullable Integer lastLikeCount,
+            int size
+    ) {
+        BooleanExpression where = feedByBooksFilter(isbn, userId);
+        if (lastLikeCount != null && lastCreatedAt != null) {
+            // likeCount DESC → createdAt DESC
+            where = where.and(
+                    feed.likeCount.lt(lastLikeCount)
+                            .or(feed.likeCount.eq(lastLikeCount)
+                                    .and(feed.createdAt.lt(lastCreatedAt)))
+            );
+        }
+
+        return jpaQueryFactory
+                .select(toQueryDto())
+                .from(feed)
+                .join(feed.userJpaEntity, user)
+                .join(feed.bookJpaEntity, book)
+                .where(where)
+                .orderBy(feed.likeCount.desc(), feed.createdAt.desc())
+                .limit(size + 1)
+                .fetch();
+    }
+
+    /**
+     * 책 ISBN으로 피드를 조회하고, 최신순 정렬하여 페이징 처리
+     */
+    @Override
+    public List<FeedQueryDto> findFeedsByBookIsbnOrderByCreatedAt(
+            String isbn,
+            Long userId,
+            @Nullable LocalDateTime lastCreatedAt,
+            int size
+    ) {
+        BooleanExpression where = feedByBooksFilter(isbn, userId);
+        if (lastCreatedAt != null) {
+            // createdAt DESC
+            where = where.and(
+                    feed.createdAt.lt(lastCreatedAt)
+            );
+        }
+
+        return jpaQueryFactory
+                .select(toQueryDto())
+                .from(feed)
+                .join(feed.userJpaEntity, user)
+                .join(feed.bookJpaEntity, book)
+                .where(where)
+                .orderBy(feed.createdAt.desc())
+                .limit(size + 1)
+                .fetch();
+    }
+
+    private QFeedQueryDto toQueryDto() {
+        return new QFeedQueryDto(
+                feed.postId,
+                feed.userJpaEntity.userId,
+                user.nickname,
+                user.aliasForUserJpaEntity.imageUrl,
+                user.aliasForUserJpaEntity.value,
+                feed.createdAt,
+                book.isbn,
+                book.title,
+                book.authorName,
+                feed.content,
+                // 서브쿼리로 N:1 방지
+                JPAExpressions
+                        .select(contentUrlAggExpr())
+                        .from(content)
+                        .where(content.postJpaEntity.postId.eq(feed.postId)),
+                feed.likeCount,
+                feed.commentCount,
+                feed.isPublic,
+                Expressions.nullExpression()
+        );
+    }
+
+    // contentUrl을 GROUP_CONCAT으로 묶어서 반환하는 표현식
+    private StringExpression contentUrlAggExpr() {
+        return Expressions.stringTemplate(
+                "group_concat({0})",
+                content.contentUrl
+        );
+    }
+
+    // 필터링 조건: 책 ISBN과 사용자 ID를 제외한 다른 사용자 공개 피드
+    private BooleanExpression feedByBooksFilter(String isbn, Long userId) {
+        return feed.status.eq(StatusType.ACTIVE)
+                .and(feed.bookJpaEntity.isbn.eq(isbn))
+                .and(feed.userJpaEntity.userId.ne(userId))
+                .and(feed.isPublic.eq(true));
+    }
 }

src/main/java/konkuk/thip/feed/application/mapper/FeedQueryMapper.java

@@ -23,6 +23,9 @@
 )
 public interface FeedQueryMapper {
 
+    /**
+     * 피드 전체 조회 응답 DTO 변환
+     */
     @Mapping(target = "aliasName", source = "dto.alias")
     @Mapping(target = "aliasColor", expression = "java(Alias.from(dto.alias()).getColor())")
     @Mapping(target = "isSaved", expression = "java(savedFeedIds.contains(dto.feedId()))")
@@ -39,6 +42,9 @@ FeedShowAllResponse.FeedDto toFeedShowAllResponse(
             @Context Long userId
     );
 
+    /**
+     * 내 피드 조회 응답 DTO 변환
+     */
     @Mapping(target = "postDate", expression = "java(DateUtil.formatBeforeTime(dto.createdAt()))")
     @Mapping(target = "isWriter", source = "dto.creatorId", qualifiedByName = "isWriter")
     FeedShowMineResponse.FeedDto toFeedShowMineDto(FeedQueryDto dto, @Context Long userId);
@@ -59,6 +65,9 @@ FeedShowByUserResponse.FeedDto toFeedShowByUserResponse(
             @Context Long userId
     );
 
+    /**
+     * 특정 유저의 피드 조회 응답 DTO 변환
+     */
     @Mapping(target = "creatorId", source = "feedOwner.id")
     @Mapping(target = "profileImageUrl", source = "feedOwner.alias.imageUrl")
     @Mapping(target = "nickname", source = "feedOwner.nickname")
@@ -70,6 +79,9 @@ FeedShowByUserResponse.FeedDto toFeedShowByUserResponse(
     @Mapping(target = "latestFollowerProfileImageUrls", source = "latestFollowerProfileImageUrls")
     FeedShowUserInfoResponse toFeedShowUserInfoResponse(User feedOwner, int totalFeedCount, boolean isFollowing, List<String> latestFollowerProfileImageUrls);
 
+    /**
+     * 피드 상세 조회 응답 DTO 변환
+     */
     @Mapping(target = "feedId", source = "feed.id")
     @Mapping(target = "creatorId", source = "feedCreator.id")
     @Mapping(target = "creatorNickname", source = "feedCreator.nickname")
@@ -121,4 +133,43 @@ default List<TagsWithCategoryResult> toTagsWithCategoryResult(List<TagCategoryQu
     default boolean isWriter(Long creatorId, @Context Long userId) {
         return creatorId != null && creatorId.equals(userId);
     }
+
+    /**
+     * 특정 책 관련 피드 조회 응답 DTO 변환
+     */
+    @Mapping(target = "feedId", source = "dto.feedId")
+    @Mapping(target = "creatorId", source = "dto.creatorId")
+    @Mapping(target = "isWriter", source = "dto.creatorId", qualifiedByName = "isWriter")
+    @Mapping(target = "creatorNickname", source = "dto.creatorNickname")
+    @Mapping(target = "creatorProfileImageUrl", source = "dto.creatorProfileImageUrl")
+    @Mapping(target = "aliasName", expression = "java(Alias.from(dto.alias()).getValue())")
+    @Mapping(target = "aliasColor", expression = "java(Alias.from(dto.alias()).getColor())")
+    @Mapping(target = "postDate", expression = "java(DateUtil.formatBeforeTime(dto.createdAt()))")
+    @Mapping(target = "isbn", source = "dto.isbn")
+    @Mapping(target = "bookTitle", source = "dto.bookTitle")
+    @Mapping(target = "bookAuthor", source = "dto.bookAuthor")
+    @Mapping(target = "contentBody", source = "dto.contentBody")
+    @Mapping(target = "contentUrls", source = "dto.contentUrls")
+    @Mapping(target = "likeCount", source = "dto.likeCount")
+    @Mapping(target = "commentCount", source = "dto.commentCount")
+    @Mapping(target = "isSaved", source = "isSaved")
+    @Mapping(target = "isLiked", source = "isLiked")
+    FeedRelatedWithBookResponse.FeedRelatedWithBookDto toFeedRelatedWithBookDto(
+            FeedQueryDto dto,
+            boolean isSaved,
+            boolean isLiked,
+            @Context Long userId
+    );
+
+    default List<FeedRelatedWithBookResponse.FeedRelatedWithBookDto> toFeedRelatedWithBookDtos(
+            List<FeedQueryDto> dtos,
+            Set<Long> savedFeedIds,
+            Set<Long> likedFeedIds,
+            @Context Long userId
+    ) {
+        return dtos.stream()
+                .map(dto -> toFeedRelatedWithBookDto(dto, savedFeedIds.contains(dto.feedId()), likedFeedIds.contains(dto.feedId()), userId))
+                .collect(Collectors.toList());
+    }
+
 }

src/main/java/konkuk/thip/feed/application/port/in/FeedRelatedWithBookUseCase.java

@@ -0,0 +1,9 @@
+package konkuk.thip.feed.application.port.in;
+
+import konkuk.thip.feed.adapter.in.web.response.FeedRelatedWithBookResponse;
+import konkuk.thip.feed.application.port.in.dto.FeedRelatedWithBookQuery;
+
+public interface FeedRelatedWithBookUseCase {
+
+    FeedRelatedWithBookResponse getFeedsByBook(FeedRelatedWithBookQuery query);
+}