MVC5 how to send string from controller to view?

Question

I have a controller that tries to download a file, if the file fails I want to send a string to the view to display the error. I'm trying to accomplish this using TempData, I'm having some trouble. The error shows when file is not downloadable, but when the file successfully downloads, the error message doesn't disappear. What might I be doing wrong?

Controller

        if (can_download)
        {

            Response.ContentType = contentType;
            Response.AppendHeader("Content-Disposition", string.Format("attachment; filename={0}", filename));
            Response.TransmitFile(path);
            Response.End();
        }
        else
        {
            TempData["AlertMessage"] = "File failed to save";

        }
        return RedirectToAction("Index", page);

View

@{
    var message = TempData["AlertMessage"];
}

<p class="error-msg">@message</p>

@section scripts {
    var message = '@message';
    if (message){
         $('.error-msg').css('opacity', 100); // show message
    }else{
         $('.error-msg').css('opacity', 0); // hide message
    }
}

afnpires · Accepted Answer · 2016-06-23 16:39:10Z

1

You have to clear the TempData if the file is generated successful.

There's a change that, in a previous error, the TempData is not consumed.

if (can_download)
    {

        Response.ContentType = contentType;
        Response.AppendHeader("Content-Disposition", string.Format("attachment; filename={0}", filename));
        Response.TransmitFile(path);
        Response.End();

        TempData["AlertMessage"] = string.Empty;

    }
    else
    {
        TempData["AlertMessage"] = "File failed to save";

    }
    return RedirectToAction("Index", page);

View

@{
    var message = TempData["AlertMessage"] as string;
}

@if (!string.IsNullOrEmpty(message)) {
 <p class="error-msg">@message</p>

@section scripts {
    var message = '@message';
    if (message){
     $('.error-msg').css('opacity', 100); // show message
    }else{
     $('.error-msg').css('opacity', 0); // hide message
    }
  }
}

edited Jun 23, 2016 at 16:39

answered Jun 23, 2016 at 16:28

afnpires

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7 Comments

ygongdev Over a year ago

Oh I see. Btw in (!string.IsNullOrEmpty(message) it says message is an object, not a string. How can I fix that?

afnpires Over a year ago

forgot the cast of TempData[... ] to string, sorry. Edited it.

ygongdev Over a year ago

Same problem still occurs :( Once I click on a undownloadable file, I get the error. Then if I click on a downloadable file, the error is still there :(

afnpires Over a year ago

Then my bet is that the view is not being refreshed on a file download. Place a DateTime.Now in the view and see if the value changes on a file download.

afnpires Over a year ago

Then I would make the TempData message disapear after 5 seconds or so with javascript.

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