public async Task <IActionResult> Invoice(Guid id) { var customerId = User.GetCustomerId(); if (customerId.HasValue) { var result = await _downloadService.DownloadInvoiceAsync(customerId.Value, id); if (result.Succeeded) { var contract = result.Value; return(File(contract.Data, contract.ContentType, contract.FileName)); } } return(View("~/Views/Error/DownloadError.cshtml")); }