public IActionResult Index(int customerId = 0) { InvoiceAdapter adapter = new InvoiceAdapter(); List <Invoice> invoices = new List <Invoice>(); if (customerId == 0) { invoices = adapter.GetAll(); } else { invoices = adapter.GetByCustomerId(customerId); } AllInvoicesModel model = new AllInvoicesModel(); List <InvoiceModels> invoiceModels = new List <InvoiceModels>(); foreach (Invoice invoice in invoices) { InvoiceModels invoiceModel = new InvoiceModels(); invoiceModel.InvoiceId = invoice.InvoiceId; invoiceModel.CustomerId = invoice.CustomerId; invoiceModel.Total = invoice.Total; invoiceModel.InvoiceDate = invoice.InvoiceDate; invoiceModels.Add(invoiceModel); } model.Invoices = invoiceModels; return(View(model)); }