public List <ProductQuantity> GetAll(int productId, int?sizeId, int?colorId) { var query = _productQuantityRepository.GetMulti(x => x.ProductId == productId, new string[] { "Color", "Size" }); if (sizeId.HasValue) { query = query.Where(x => x.SizeId == sizeId); } if (colorId.HasValue) { query = query.Where(x => x.ColorId == colorId); } return(query.ToList()); }