public static IQueryable<Petshop.Data.Entities.Cart> ByProductId(this IQueryable<Petshop.Data.Entities.Cart> queryable, System.String productId, params System.String[] additionalValues)
        {
            var productIdList = new List<System.String> { productId };

            if (additionalValues != null)
                productIdList.AddRange(additionalValues);

            if (productIdList.Count == 1)
                return queryable.ByProductId(productIdList[0]);

            return queryable.ByProductId(productIdList);
        }
        public static IQueryable<PetShop.Core.Data.Item> ByProductId(this IQueryable<PetShop.Core.Data.Item> queryable, string productId, params string[] additionalValues)
        {
            var productIdList = new List<string> { productId };

            if (additionalValues != null)
                productIdList.AddRange(additionalValues);

            if (productIdList.Count == 1)
                return queryable.ByProductId(productIdList[0]);

            return queryable.ByProductId(productIdList);
        }