XAML Named element not found by FindName

Question

I am having problems finding an named object declared in XAML in my codebehind file.

I want to initalize a ViewModel from inside my View. However I also need a reference to the ViewModel in my code behind file (basically for navigation support, handling events, etc. that I cannot do easily from my ViewModel)

<navigation:Page.DataContext>
    <vm:JobsViewModel x:Name="ViewModel" />
</navigation:Page.DataContext>

However I get a null reference exception when I'm trying to access the ViewModel in my code behind:

    Protected Overrides Sub OnNavigatedTo(ByVal e As System.Windows.Navigation.NavigationEventArgs)
        MyBase.OnNavigatedTo(e)
        ViewModel.Initalize() '<-- Exception here
    End Sub

Some more research shows that the FindName call for "ViewModel" in InitalizeComponent returns null. I tried reading up on XAML namescopes etc. but as far as I see, this should be a simple case and just work, no?

Any pointers as to why this fails would be greatly appreciated. Thanks!

Answer 1

That's because your JobsViewModel is not part of the visual tree, so FindName doesn't find it. You can retrieve it through the DataContext property instead.