Feat: 제품 상세, 홈 화면에 좋아요 여부 추가

src/main/java/com/DecodEat/domain/products/controller/ProductController.java

@@ -67,8 +67,8 @@ public ApiResponse<ProductRegisterResponseDto> registerProduct(
     )
     @GetMapping("/latest")
     public ApiResponse<ProductResponseDTO.ProductListResultDTO> getProductList(
-            @RequestParam(required = false) Long cursorId) {
-        return ApiResponse.onSuccess(productService.getProducts(cursorId));
+            @RequestParam(required = false) Long cursorId, @OptionalUser User user) {
+        return ApiResponse.onSuccess(productService.getProducts(cursorId, user));
     }
 
     @GetMapping("/search/autocomplete")

src/main/java/com/DecodEat/domain/products/converter/ProductConverter.java

@@ -10,14 +10,16 @@
 
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 import java.util.stream.Collectors;
 
 import static com.DecodEat.domain.products.entity.RawMaterial.RawMaterialCategory.*;
 
 public class ProductConverter {
     public static ProductDetailDto toProductDetailDto(Product product,
                                                       List<String> productInfoImageUrls ,
-                                                      ProductNutrition productNutrition) {
+                                                      ProductNutrition productNutrition,
+                                                      boolean isLiked) {
         Map<RawMaterialCategory, List<String>> nutrientsMap =
                 product.getIngredients().stream()
                         .collect(Collectors.groupingBy(
@@ -35,6 +37,7 @@ public static ProductDetailDto toProductDetailDto(Product product,
                 .name(product.getProductName())
                 .manufacturer(product.getManufacturer())
                 .productImage(product.getProductImage())
+                .isLiked(isLiked)
                 .calcium(productNutrition.getCalcium())
                 .carbohydrate(productNutrition.getCarbohydrate())
                 .cholesterol(productNutrition.getCholesterol())
@@ -67,13 +70,14 @@ public static ProductRegisterResponseDto toProductRegisterDto(Product product, L
     }
 
     // 단일 Product → ProductListItemDTO 변환
-    public static ProductResponseDTO.ProductListItemDTO toProductListItemDTO(Product product){
+    public static ProductResponseDTO.ProductListItemDTO toProductListItemDTO(Product product, boolean isLiked) {
         return ProductResponseDTO.ProductListItemDTO.builder()
                 .productId(product.getProductId())
                 .manufacturer(product.getManufacturer())
                 .productName(product.getProductName())
                 .productImage(product.getProductImage())
                 .decodeStatus(product.getDecodeStatus())
+                .isLiked(isLiked)
                 .build();
     }
 
@@ -105,9 +109,9 @@ public static ProductRegisterHistoryDto toProductRegisterHistoryDto(Product prod
 
 
     // Slice<Product> → ProductListResultDTO 변환
-    public static ProductResponseDTO.ProductListResultDTO toProductListResultDTO(Slice<Product> slice) {
+    public static ProductResponseDTO.ProductListResultDTO toProductListResultDTO(Slice<Product> slice, Set<Long> likedProductIds) {
         List<ProductResponseDTO.ProductListItemDTO> productList = slice.getContent().stream()
-                .map(ProductConverter::toProductListItemDTO)
+                .map(product -> toProductListItemDTO(product, likedProductIds.contains(product.getProductId())))
                 .toList();
 
         Long nextCursorId = (slice.hasNext() && !productList.isEmpty())

src/main/java/com/DecodEat/domain/products/dto/response/ProductDetailDto.java

@@ -25,6 +25,8 @@ public class ProductDetailDto {
 
     private List<String> imageUrl;
 
+    private boolean isLiked;
+
     private Double calcium;
     private Double carbohydrate;
     private Double cholesterol;

src/main/java/com/DecodEat/domain/products/dto/response/ProductResponseDTO.java

@@ -55,6 +55,9 @@ public static class ProductListItemDTO {
 
         @Schema(description = "뷴석 상태", example = "COMPLETED")
         private DecodeStatus decodeStatus;
+
+        @Schema(description = "좋아요 여부", example = "true")
+        private boolean isLiked;
     }
 
 }

src/main/java/com/DecodEat/domain/products/repository/ProductLikeRepository.java

@@ -4,11 +4,23 @@
 import com.DecodEat.domain.products.entity.ProductLike;
 import com.DecodEat.domain.users.entity.User;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
 
+import java.util.List;
 import java.util.Optional;
 
 public interface ProductLikeRepository extends JpaRepository<ProductLike, Long>  {
 
     Optional<ProductLike> findByUserAndProduct(User user, Product product);
 
+    // 여러 제품에 대한 좋아요 여부 조회 ( 제품 리스트 조회시 N + 1 문제 해결)
+    @Query("SELECT pl.product.productId " +
+            "FROM ProductLike pl " +
+            "WHERE pl.user = :user AND pl.product.productId IN :productIds")
+    List<Long> findLikedProductIdsByUserAndProductIds(@Param("user") User user,
+                                                      @Param("productIds") List<Long> productIds);
+
+    boolean existsByUserAndProduct(User user, Product product);
+
 }

src/main/java/com/DecodEat/domain/products/service/ProductService.java

@@ -27,10 +27,7 @@
 import org.springframework.web.multipart.MultipartFile;
 
 import javax.swing.*;
-import java.util.ArrayList;
-import java.util.List;
-import java.util.Optional;
-import java.util.UUID;
+import java.util.*;
 import java.util.stream.Collectors;
 
 import static com.DecodEat.global.apiPayload.code.status.ErrorStatus.*;
@@ -62,7 +59,12 @@ public ProductDetailDto getDetail(Long id, User user) {
 
         ProductNutrition productNutrition = productNutritionRepository.findByProduct(product).orElseThrow(() -> new GeneralException(PRODUCT_NUTRITION_NOT_EXISTED));
 
-        return ProductConverter.toProductDetailDto(product, imageUrls, productNutrition);
+        // 좋아요 여부 확인
+        boolean isLiked = false;
+        if(user != null){
+            isLiked = productLikeRepository.existsByUserAndProduct(user,product);
+        }
+        return ProductConverter.toProductDetailDto(product, imageUrls, productNutrition, isLiked);
     }
 
     public ProductRegisterResponseDto addProduct(User user, ProductRegisterRequestDto requestDto, MultipartFile productImage, List<MultipartFile> productInfoImages) {
@@ -110,11 +112,25 @@ public ProductRegisterResponseDto addProduct(User user, ProductRegisterRequestDt
     }
 
     @Transactional(readOnly = true)
-    public ProductResponseDTO.ProductListResultDTO getProducts(Long cursorId) {
+    public ProductResponseDTO.ProductListResultDTO getProducts(Long cursorId, User user) {
         Pageable pageable = PageRequest.of(0, PAGE_SIZE);
         Slice<Product> slice = productRepository.findCompletedProductsByCursor(cursorId, pageable);
 
-        return ProductConverter.toProductListResultDTO(slice);
+        // 기본값: 전부 false
+        Set<Long> likedProductIds = Collections.emptySet();
+
+        // user가 null이 아닐 때만 DB에서 좋아요 여부 조회
+        if (user != null && !slice.isEmpty()) {
+            List<Long> productIds = slice.getContent().stream()
+                    .map(Product::getProductId)
+                    .toList();
+
+            likedProductIds = new HashSet<>(
+                    productLikeRepository.findLikedProductIdsByUserAndProductIds(user, productIds)
+            );
+        }
+
+        return ProductConverter.toProductListResultDTO(slice, likedProductIds);
     }
 
     // todo: 검색은 상품 엔티티와 1:1 매핑 불가능 -> userbehavior 어떻게?