private void GetQuantityByCompanyItem(StockInViewModel stockInViewModel) { stockInViewModel = stockInManager.GetQuantityByCompanyAndItem(stockInViewModel); //availableQuantityTextBox.Text = stockInModel.AvailableQuantity.ToString(); if (stockInViewModel == null) { availableQuantityTextBox.Text = "0"; } else { availableQuantityTextBox.Text = stockInViewModel.Quantity.ToString(); } }