public void AddQuantity(string modelno, int code, int quantity) { myShop.ProductDeserialize(ref myShop); dgvData.DataSource = myShop.ProductList; bool result = myShop.AddExistingProduct(modelno, code, quantity); if (result) { MessageBox.Show(Filepath.QuantityAdded); myShop.ProductSerialize(ref myShop); Reset(); } else { MessageBox.Show("Enter valid ModelNo and the corresponding code"); txtCode.Clear(); txtModel.Clear(); } }