Send error message to user (ASP.NET MVC)

Question

I have the following situation: in my controller MovementsController got an action Details who is responsible for performing a database search through the Id received. The question is: if no data is found in the database how do I direct the user to an error page containing the reason for the error (in case the property Message of the type object Exception)? All I’ve been able to do so far is launch a HttpException for the user to be directed to a custom page NotFound.cshtml, as set out in Web.config.

Action Details:

    // GET: Movements/Details
    public ActionResult Details (int? Id)
    {
        try
        {
            return View(_service.GetById(Id.GetValueOrDefault()));
        }
        catch (ApplicationException e)
        {
            if (e is NotFoundException)
                throw new HttpException();
            else
                return RedirectToAction(nameof(Index));
        }
    } 

Web.config:

<customErrors mode="On" defaultRedirect="~/Errors/Error">
  <error statusCode="404" redirect="~/Errors/NotFound" />
</customErrors>

Answer 1

You don’t necessarily need an Exception to run the customErrors, you can simply return the Status Code you want:

catch (ApplicationException e) when (e is NotFoundException)
{
     return NotFound();
}
catch (ApplicationException e)
{
     return RedirectToAction(nameof(Index));
}

As there will be a redirect, you would need to store the error message somewhere, I suggest using the TempData:

catch (ApplicationException e) when (e is NotFoundException)
{
     TempData["ErrorMessage"] = e.Message;
     return NotFound();
}

And then use in View of error:

@TempData["ErrorMessage"].ToString()

If you don’t want to store these values, you could also redirect to the error action using the RedirectToAction passing the error message as a parameter.