Proper coded examples of MVC 3 error handling

I'm coming from the Winforms world where I trapped everything and handled errors with messages to the user with MessageBox.Show(ex.message) or just logged it. Now I'm in the web (MVC 3) world and I can't seem to find a definitive coded example of how to employ proper error handling. Let me show you what I'm using:

User clicks on a link which runs a controller action:

Function SelectAlertKPIs() As ActionResult

    Try
        Return PartialView()

    Catch ex As Exception
        TempData("ErrorMessage") = "There was a problem during page load: " & ex.Message & vbCrLf & vbCrLf & ex.StackTrace
        Return RedirectToAction("HttpError", "Error")
    End Try

End Function

This view loads a Telerik grid with AJAX binding, so now the binding runs this action:

<GridAction()> _
Function _SelectAlertKPIs() As ActionResult

    Try
        Return PartialView(New GridModel(AlertKPIRepository.All()))

    Catch ex As Exception
        TempData("ErrorMessage") = "There was a problem during page load: " & ex.Message & vbCrLf & vbCrLf & ex.StackTrace
        Return RedirectToAction("HttpError", "Error")
    End Try

End Function

Which calls this method to get data:

Public Shared Function All() As IList(Of AlertKPI)

    Dim l As IList(Of AlertKPI) = Nothing

    Try
        Using dc As New AdminAlertKPIDataContext(TripleDESSecurity.Decrypt(SharedData.PortalCnx))
            l = (From d In dc.AdminAlertKPIs Order By d.ID Select New AlertKPI With {
                .ID = d.ID,
                .KPI = d.KPI,
                .KPIName = d.KPIName,
                .KPIDescription = d.KPIDescription
            }).ToList
        End Using

        Return l

    Catch ex As Exception
        Throw
    Finally
        If Not l Is Nothing Then l = Nothing
    End Try

End Function

These are my ErrorController actions:

Public Function HttpError() As ActionResult

    Dim s As String = String.Empty

    s = TempData("ErrorMessage")
    ViewData("ErrorMessage") = "An error occurred. " & s

    Return PartialView("Error")

End Function

Public Function Http404() As ActionResult

    Try
        ViewData("ErrorMessage") = "The page you requested could not be found"

        Retu开发者_Go百科rn View("Error")

    Catch ex As Exception
        Return View("Error")
    End Try

End Function

This is what I have in my web.config:

<customErrors mode="On" defaultRedirect="/Error/HttpError">
  <error statusCode="404" redirect="/Error/Http404" />
</customErrors>

Now if I add code into my controller action to purposely throw:

Throw New HttpUnhandledException

Then it falls to the catch block, and then routes to the HttpError action.. Twice! and then my Error.aspx view never opens, instead I get either no JSON result or a 500 internal server error... makes not a lick of sense to me. Basically, I don't know what I'm doing.

And I could use some really good guidance....

You need to look into [HandleErrorAttribute] - there is no need to polute your action methods with try catch blocks. You might want to implement your own error handler attribute for additional logging - which is what I'm doing today. This is today's post on exception handling: click here

Your web config is for exceptions that occur outside of MVC application pipeline. IIS will be able to read the web config and then re-direct user to the correct page. Others, please correct me if I'm wrong as I only started looking at this today.