public ProductAddModel()
 {
     Product = new Product();
     ListOfProductItem = new List<ProductItem>();
     ListOfRawMaterial = new List<RawMaterial>();
     OldProductItemIds = new List<string>();
     NewProductItemIds = new List<string>();
 }
 public QuoteProductModel()
 {
     ProductSample = new ProductSample();
     Product = new Product();
     ListOfProductRawMaterial = new List<ProductRawMaterial>();
 }