feat: 상품 필터링 기능 개선

- 브랜드 필터링을 단일 → 다중 선택으로 변경 (brandIds)
- 사이즈 필터링을 단일 → 다중 선택으로 변경 (clothingSizes)
- 가격 필터링 시 할인가(discountPrice) 기준으로 적용되도록 수정
- 사이즈 REGEXP 패턴으로 정확한 값 매칭 처리 (S가 XS에 매칭되는 버그 수정)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: kangcheolung

src/main/java/com/ongil/backend/domain/product/controller/ProductController.java

@@ -73,18 +73,18 @@ public DataResponse<List<ProductOptionResponse>> getProductOptions(
 	public DataResponse<ProductSearchPageResDto> getProducts(
 		@RequestParam(required = false) String query,
 		@RequestParam(required = false) Long categoryId,
-		@RequestParam(required = false) Long brandId,
+		@RequestParam(required = false) List<Long> brandIds,
 		@RequestParam(required = false) String priceRange,
-		@RequestParam(required = false) String clothingSize,
+		@RequestParam(required = false) List<String> clothingSizes,
 		@RequestParam(required = false, defaultValue = "POPULAR") ProductSortType sortType,
 		@PageableDefault(size = 20) Pageable pageable,
 		@AuthenticationPrincipal Long userId
 	) {
 		ProductSearchCondition condition = ProductSearchCondition.builder()
 			.categoryId(categoryId)
-			.brandId(brandId)
+			.brandIds(brandIds != null && !brandIds.isEmpty() ? brandIds : null)
 			.priceRange(priceRange)
-			.size(clothingSize)
+			.sizes(clothingSizes != null && !clothingSizes.isEmpty() ? clothingSizes : null)
 			.build();
 
 		ProductSearchPageResDto res = productService.getProducts(condition, sortType, pageable, query, userId);

src/main/java/com/ongil/backend/domain/product/dto/request/ProductSearchCondition.java

@@ -1,5 +1,7 @@
 package com.ongil.backend.domain.product.dto.request;
 
+import java.util.List;
+
 import io.swagger.v3.oas.annotations.media.Schema;
 import lombok.Builder;
 import lombok.Getter;
@@ -12,14 +14,23 @@ public class ProductSearchCondition {
 	@Schema(description = "카테고리 ID", example = "1")
 	private Long categoryId;
 
-	@Schema(description = "브랜드 ID", example = "5")
-	private Long brandId;
+	@Schema(description = "브랜드 ID 목록 (다중 선택)", example = "[1, 2, 3]")
+	private List<Long> brandIds;
 
 	@Schema(description = "가격 범위 (형식: minPrice-maxPrice)", example = "50000-100000")
 	private String priceRange;
 
-	@Schema(description = "사이즈 (예: XS, S, M, L, XL)", example = "M")
-	private String size;
+	@Schema(description = "사이즈 목록 (다중 선택, 예: XS, S, M, L, XL)", example = "[M, L]")
+	private List<String> sizes;
+
+	// 사이즈 목록을 REGEXP 패턴으로 변환 (예: [M, L] → "(^|,)(M|L)(,|$)")
+	public String buildSizesPattern() {
+		if (sizes == null || sizes.isEmpty()) {
+			return null;
+		}
+		String sizeGroup = String.join("|", sizes);
+		return "(^|,)(" + sizeGroup + ")(,|$)";
+	}
 
 	// 가격 범위 파싱
 	public Integer[] parsePriceRange() {

src/main/java/com/ongil/backend/domain/product/repository/ProductRepository.java

@@ -44,19 +44,23 @@ public interface ProductRepository extends JpaRepository<Product, Long> {
     SELECT p FROM Product p
     WHERE (:targetIds IS NULL OR p.id IN :targetIds)
       AND (:categoryId IS NULL OR p.category.id = :categoryId)
-      AND (:brandId IS NULL OR p.brand.id = :brandId)
-      AND (:minPrice IS NULL OR p.price >= :minPrice)
-      AND (:maxPrice IS NULL OR p.price <= :maxPrice)
-      AND (:size IS NULL OR p.sizes LIKE CONCAT('%', :size, '%'))
+      AND (:brandIds IS NULL OR p.brand.id IN :brandIds)
+      AND (:minPrice IS NULL OR
+          (p.discountPrice IS NOT NULL AND p.discountPrice > 0 AND p.discountPrice >= :minPrice)
+          OR ((p.discountPrice IS NULL OR p.discountPrice = 0) AND p.price >= :minPrice))
+      AND (:maxPrice IS NULL OR
+          (p.discountPrice IS NOT NULL AND p.discountPrice > 0 AND p.discountPrice <= :maxPrice)
+          OR ((p.discountPrice IS NULL OR p.discountPrice = 0) AND p.price <= :maxPrice))
+      AND (:sizesPattern IS NULL OR FUNCTION('REGEXP_LIKE', p.sizes, :sizesPattern) = true)
       AND p.onSale = true
     """)
 	Page<Product> findAllByCondition(
 		@Param("targetIds") List<Long> targetIds,
 		@Param("categoryId") Long categoryId,
-		@Param("brandId") Long brandId,
+		@Param("brandIds") List<Long> brandIds,
 		@Param("minPrice") Integer minPrice,
 		@Param("maxPrice") Integer maxPrice,
-		@Param("size") String size,
+		@Param("sizesPattern") String sizesPattern,
 		Pageable pageable
 	);
 
@@ -66,19 +70,23 @@ Page<Product> findAllByCondition(
     SELECT p FROM Product p
     WHERE (:targetIds IS NULL OR p.id IN :targetIds)
       AND p.category.parentCategory.id = :parentCategoryId
-      AND (:brandId IS NULL OR p.brand.id = :brandId)
-      AND (:minPrice IS NULL OR p.price >= :minPrice)
-      AND (:maxPrice IS NULL OR p.price <= :maxPrice)
-      AND (:size IS NULL OR p.sizes LIKE CONCAT('%', :size, '%'))
+      AND (:brandIds IS NULL OR p.brand.id IN :brandIds)
+      AND (:minPrice IS NULL OR
+          (p.discountPrice IS NOT NULL AND p.discountPrice > 0 AND p.discountPrice >= :minPrice)
+          OR ((p.discountPrice IS NULL OR p.discountPrice = 0) AND p.price >= :minPrice))
+      AND (:maxPrice IS NULL OR
+          (p.discountPrice IS NOT NULL AND p.discountPrice > 0 AND p.discountPrice <= :maxPrice)
+          OR ((p.discountPrice IS NULL OR p.discountPrice = 0) AND p.price <= :maxPrice))
+      AND (:sizesPattern IS NULL OR FUNCTION('REGEXP_LIKE', p.sizes, :sizesPattern) = true)
       AND p.onSale = true
     """)
 	Page<Product> findAllByParentCategoryCondition(
 		@Param("targetIds") List<Long> targetIds,
 		@Param("parentCategoryId") Long parentCategoryId,
-		@Param("brandId") Long brandId,
+		@Param("brandIds") List<Long> brandIds,
 		@Param("minPrice") Integer minPrice,
 		@Param("maxPrice") Integer maxPrice,
-		@Param("size") String size,
+		@Param("sizesPattern") String sizesPattern,
 		Pageable pageable
 	);
 

src/main/java/com/ongil/backend/domain/product/service/ProductService.java

@@ -160,21 +160,21 @@ public ProductSearchPageResDto getProducts(
 				products = productRepository.findAllByParentCategoryCondition(
 					targetIds,
 					condition.getCategoryId(),
-					condition.getBrandId(),
+					condition.getBrandIds(),
 					minPrice,
 					maxPrice,
-					condition.getSize(),
+					condition.buildSizesPattern(),
 					pageableWithSort
 				);
 			} else {
 				// 하위 카테고리 → 해당 카테고리 상품만 조회
 				products = productRepository.findAllByCondition(
 					targetIds,
 					condition.getCategoryId(),
-					condition.getBrandId(),
+					condition.getBrandIds(),
 					minPrice,
 					maxPrice,
-					condition.getSize(),
+					condition.buildSizesPattern(),
 					pageableWithSort
 				);
 			}
@@ -183,10 +183,10 @@ public ProductSearchPageResDto getProducts(
 			products = productRepository.findAllByCondition(
 				targetIds,
 				null,
-				condition.getBrandId(),
+				condition.getBrandIds(),
 				minPrice,
 				maxPrice,
-				condition.getSize(),
+				condition.buildSizesPattern(),
 				pageableWithSort
 			);
 		}