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?

Answer 1

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));
    }