MVC Requesting File Download - how to handle no file available?

Question

I'm relatively new to MVC but suppose I have a @Html.ActionLink(.... on my page that links to an Action that generates a file and returns it using:

return File(memoryStream, "application/vnd.ms-excel");

This all works well until there's some kind of issue - either something's gone wrong or there's no file to return.

Returning null makes the webpage go to a blank page. So my question is... How can I gracefully handle this scenario? - ideally displaying some error to the user that something went wrong or there's no file/data available or if this isn't possible, then just ensuring the page doesn't go to a blank page, and just remains as it is.

I suppose I could redirect to the index action but this will refresh the page - are there any alternatives.

I assume you are working with a file result....you need to add a condition just like in this answer: http://stackoverflow.com/questions/11434345/redirecting-to-mvc-actionresult-from-fileresult — Hackerman, May 19 '16 at 16:10
Can you render the actionlink only if the file exists? `File.Exists(pathToFile)` — Nick, May 19 '16 at 16:11
@NicholasV. unfortunately no as the file is generated from the database, I would have do do all the "file processing" on the page load. — Percy, May 19 '16 at 16:28
@Hackerman - exactly the same situation but the answer is what I'm trying to avoid - reloading the page or another page. — Percy, May 19 '16 at 16:29

score 1 · Answer 1 · answered May 19 '16 at 16:17

I would do one of two things:

Return a 404 Not Found response:
```
return HttpNotFound();
```

Render a "friendly" error page:

try
{
    if (File.Exists(...))
    {
        // Download file
    }
    else
    {
        return View("FileNotFound");
    }
}
catch (Exception ex)
{
    return View("FileError", ex);
}

MVC Requesting File Download - how to handle no file available?

1 Answers1