不使用 Return 执行 FileContentResult

Question

How can i download csv file without ending The Action by using return Command?

I want to have an action that can download a csv file and continue with action logic. is it possible to initiate a request without actually end the action and return back from the controller? something like that:

public IActionResult AddOrdersExtension(OrderVM orderVM)
{
  if (ModelState.IsValid)
     {
        StringBuilder sb = new StringBuilder();
         //Header             
     sb.Append("Product,Empty,Name,Address1,Address2,City,State,zip,Country,Phone,Quantity,Weight");
                FileContentResult fr = File(Encoding.ASCII.GetBytes(sb.ToString()), "text/csv", 
      "Error_log.csv");
//
//execute csv download
//
// continue with function

return View(orderVM.Orders); // return from action when logic is done
}//end function

Answer 1

From your codes, the following is an in-memory operation:

FileContentResult fr = File(Encoding.ASCII.GetBytes(sb.ToString()), "text/csv", 
      "Error_log.csv");

Do download the file from the server again you need to store the file. Not sure why you want to download the file here, But if you want you can save the file to a temporary folder: download and then remove the file like this:

FileContentResult fr = File(Encoding.ASCII.GetBytes(sb.ToString()), "text/csv", "Error_log.csv");

//For concurrent access use dynamic name file names

//Save to disk

File.WriteAllBytes( "~/tmp/Error_log.csv", ((FileContentResult)fr).FileContents);

//Download

string remoteUri = "http://www.yourdomain.com/tmp/";
string fileName = "Error_log.csv_downloaded", myStringWebResource = null;

// Create a new WebClient instance and download the file

using (WebClient myWebClient = new WebClient())
{
    myStringWebResource = remoteUri + fileName;
    // Download the Web resource and save it into the current filesystem folder.
    myWebClient.DownloadFile(myStringWebResource, fileName);        
}

//Delete both the files

var fullPath = Server.MapPath("~/tmp/Error_log.csv");

        if (File.Exists(fullPath))
        {
            File.Delete(fullPath);
        }

fullPath = Server.MapPath("~/tmp/Error_log.csv_downloaded");

        if (File.Exists(fullPath))
        {
            File.Delete(fullPath);
        }

There might be some syntax errors and reference libraries to be added. But I hope you get the solution you are looking for.