RelativeSource binding not resolving

Question

I have a ContextMenu in a TreeView

UserControl (DataContext=ViewModel)
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    |
    ---- TreeView (ItemSource=MyItems)
           |
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Answer 1

Finally, after many many many google searches I ran into the solution

<MenuItem
    Header="Exclude season"
    Command="{Binding DataContext.MyRelayCommand, Source={x:Reference _myTreeView}}" />

Because the HierarchicalDataTemplate does not appear in the visual tree, there is not "relative" source...

I hope this helps somebody else who's pulling his/her hair out...

Answer 2

Another commonly used solution:

<ContextMenu DataContext="{Binding RelativeSource={RelativeSource Self}, Path=PlacementTarget.DataContext}" />