feat: 도서와 관련된 리뷰 개수 조회 API 추가 (#119)

src/main/java/com/jisungin/api/review/ReviewController.java

@@ -29,6 +29,11 @@ public ApiResponse<SliceResponse<ReviewWithRatingResponse>> findBookReviews(
         return ApiResponse.ok(reviewService.findBookReviews(isbn, OffsetLimit.of(page, size, order)));
     }
 
+    @GetMapping("/books/{isbn}/reviews/count")
+    public ApiResponse<Long> findBookReviewsCount(@PathVariable String isbn) {
+        return ApiResponse.ok(reviewService.findBookReviewsCount(isbn));
+    }
+
     @PostMapping("/reviews")
     public ApiResponse<Void> createReview(@Valid @RequestBody ReviewCreateRequest request,
                                           @Auth Long userId) {

src/main/java/com/jisungin/application/review/ReviewService.java

@@ -37,6 +37,13 @@ public SliceResponse<ReviewWithRatingResponse> findBookReviews(String isbn, Offs
                 offsetLimit.getOrder());
     }
 
+    public Long findBookReviewsCount(String isbn) {
+        Book book = bookRepository.findById(isbn)
+                .orElseThrow(() -> new BusinessException(BOOK_NOT_FOUND));
+
+        return reviewRepository.countByBookId(book.getIsbn());
+    }
+
     @Transactional
     public void createReview(ReviewCreateServiceRequest request, Long userId) {
         User user = userRepository.findById(userId)

src/main/java/com/jisungin/domain/review/repository/ReviewRepositoryCustom.java

@@ -13,4 +13,6 @@ PageResponse<ReviewContentResponse> findAllReviewContentOrderBy(
 
     SliceResponse<ReviewWithRatingResponse> findAllByBookId(String isbn, Integer offset, Integer limit, String order);
 
+    Long countByBookId(String isbn);
+
 }

src/main/java/com/jisungin/domain/review/repository/ReviewRepositoryImpl.java

@@ -96,6 +96,14 @@ private List<ReviewContentResponse> getReviewContents(
                 .fetch();
     }
 
+    public Long countByBookId(String isbn) {
+        return queryFactory.select(review.count())
+                .from(review)
+                .join(review.book, book)
+                .where(book.isbn.eq(isbn))
+                .fetchOne();
+    }
+
     private long getTotalCount(Long userId, Double rating) {
         return queryFactory
                 .select(review.count())