NavigationService.Navigate error

Question

I'm quite new on C# programming and I have a problem on my code. I have created a button and applied on it an event click which open an other page of my project by the technology NavigationService.

This is the script:

private void click_login(object sender, RoutedEventArgs e)
{
    NavigationService nav = NavigationService.GetNavigationService(this); 
    nav.Navigate(new Uri("Window1.xaml", UriKind.RelativeOrAbsolute));
}

When I execute, I get this error:

The object reference is not set to an instance of an object with an InnerException null.

Can you help me please?

did you checked if nav is not null when your debugging this ? and here a some Remarks when GetNavigationService returns null — Mark
You have seen right, nav in null. Do I have to initiate with "new"? — Kraenys
No, please check the link i've provided in the remarks section there is a description when the GetNavigationService-Method returns null. There's probably something wrong with the this you are handing over to the method. — Mark
This returns 2 things: WpfApplication3.MainWindow which only have "InitializeComponent();" for the moment and the second thing is my button in mainwindow.xaml Is that mean there's a conflict about what "this" mean? — Kraenys

Mark Mark · Accepted Answer · 2014-08-11T09:05:36

Your nav object is null, because you're trying to get the NavigationService for a WPF Window.

But for Navigation you need a Page (Navigation Overview on MSDN)

A Little Working example:

Create to Page's Page1.xaml, Page2.xaml

In the App.xaml change the StartupUri to StartupUri="Page1.xaml"

Page1 Xaml:

 <StackPanel>
     <TextBlock Text="Hello from  Page1" />
     <Button Click="Button_Click" Content="Navigate to page 2"></Button>
 </StackPanel>

Page1 cs:

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        NavigationService nav = NavigationService.GetNavigationService(this);
        nav.Navigate(new Uri("Page2.xaml", UriKind.RelativeOrAbsolute));
    }

Page2 Xaml:

 <StackPanel>
     <TextBlock Text="Hello from  Page2" />
     <Button Click="Button_Click" Content="Navigate to page 1"></Button>
 </StackPanel>

Page2 cs:

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        NavigationService nav = NavigationService.GetNavigationService(this);
        nav.Navigate(new Uri("Page1.xaml", UriKind.RelativeOrAbsolute));
    }

NavigationService.Navigate error

1 Answers