Can't fetch Page.RouteData.Values in vb.net

Question

I am trying to enable routing on an asp vb.net application.

I followed the next steps :

1) In global.asax,there is this code

<%@ Application Language="VB" %>
<%@ Import Namespace="System.Web.Optimization" %>
<%@ Import Namespace="System.Web.Routing" %>

<script runat="server">

    Sub Application_Start(sender As Object, e As EventArgs)
        RouteConfig.RegisterRoutes(RouteTable.Routes)
        BundleConfig.RegisterBundles(BundleTable.Bundles)
    End Sub
</script>

2) In the RouteConfig.vb i have this :

Imports System.Web
Imports System.Web.Routing
Imports Microsoft.AspNet.FriendlyUrls

Public Module RouteConfig

    Public Sub RegisterRoutes(routes As RouteCollection)
        Dim settings = New FriendlyUrlSettings()
        settings.AutoRedirectMode = RedirectMode.Permanent
        routes.EnableFriendlyUrls(settings)
        routes.MapPageRoute("Services",
            "Services/{SID}",
            "~/Services.aspx")
    End Sub

End Module

3) In the services.aspx page, i wrote this

Imports System.Web.Routing Partial Class Services Inherits System.Web.UI.Page

Protected Sub Page_Load(sender As Object, e As EventArgs) Handles Me.Load
    If Not Me.IsPostBack Then
        lblTest.Text = RouteData.Values("SID").ToString
    End If
End Sub

End Class

When I run the page, I get the error message

"No object reference is specified in an object instance."

If I delete the line "lblTest.Text = RouteData.Values("SID").ToString" it is working, of course without the SID parameter

Sorry for bad english.

score 0 · Accepted Answer · answered Sep 28 '17 at 04:08

"No object reference is specified in an object instance" known as another wording to indicate NullReferenceException besides common "Object reference not set to an instance of an object" message. Since you're mentioning this line:

lblTest.Text = RouteData.Values("SID").ToString

The exception occurs when RouteData.Values("SID") contains Nothing, and ToString cannot work with Nothing set as its source string. You can check if RouteData.Values has Nothing using RouteData.Values.ContainsKey:

If (Page.RouteData.Values.ContainsKey("SID")) Then
    lblTest.Text = RouteData.Values("SID").ToString
End If

Since you're using MapPageRoute with FriendlyUrls, I think you need to rename URL in second argument to another different name than physical ASPX file name, preventing Nothing passed as URL argument:

' note 's' omitted in Service/{SID} route
routes.MapPageRoute("Services", "Service/{SID}", "~/Services.aspx")

Then, you can try reordering statements inside RegisterRoutes so that EnableFriendlyUrls executed after MapPageRoute:

Public Module RouteConfig

    Public Sub RegisterRoutes(routes As RouteCollection)
        routes.MapPageRoute("Services", "Service/{SID}", "~/Services.aspx")

        Dim settings = New FriendlyUrlSettings()
        settings.AutoRedirectMode = RedirectMode.Permanent
        routes.EnableFriendlyUrls(settings)
    End Sub

End Module

Similar issues:

FriendlyURLs - RouteData returns no value

Page.RouteData.Values are empty for one page but not another

Can't fetch Page.RouteData.Values in vb.net

1 Answers1