WPF: programmatically opening context menu loses data context - wpf

Question

I would like to reuse the context menu of a ListViewItem by adding a toggle button within the item itself which opens it.
The context menu itself works correctly,
however when I open it through the toggle button (simply setting its property IsOpen to True) the commands inside don't work anymore.
It seems the context menu does not have the DataContext anymore.
<ListView>
<ListView.ItemContainerStyle>
<Style TargetType="{x:Type ListViewItem}">
<Setter Property="ContextMenu">
<Setter.Value>
<ContextMenu>
<MenuItem
Header="Restore"
Command="{Binding RestoreCommand}" />
<MenuItem
Header="Delete"
Command="{Binding DeleteCommand}"/>
</ContextMenu>
</Setter.Value>
</Setter>
</Style>
</ListView.ItemContainerStyle>
<ListView.View>
<GridView>
<!-- My columns here -->
<GridViewColumn>
<GridViewColumn.CellTemplate>
<DataTemplate>
<ToggleButton IsChecked="{Binding Path=ContextMenu.IsOpen, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ListViewItem}}}"/>
</DataTemplate>
</GridViewColumn.CellTemplate>
</GridViewColumn>
</GridView>
</ListView.View>
Any suggestions?
Thanks

Answer 1

The issue is that the context menu opened indirectly in this way does not have a DataContext.
In order to "assign" it one, you should use the property PlacementTarget to indicate on which control it is bound to.
To achieve this task you can either create a custom behavior, or, if you prefer a purely xaml solution:
<!-- xmlns:b="http://schemas.microsoft.com/xaml/behaviors" -->
<GridViewColumn>
<GridViewColumn.CellTemplate>
<DataTemplate>
<ToggleButton
x:Name="MoreActionsButton"
IsChecked="{Binding ContextMenu.IsOpen, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ListViewItem}}, Mode=OneWayToSource}">
<b:Interaction.Triggers>
<b:EventTrigger EventName="Checked">
<b:ChangePropertyAction
TargetObject="{Binding ContextMenu, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ListViewItem}}}"
PropertyName="PlacementTarget"
Value="{Binding ElementName=MoreActionsButton}" />
</b:EventTrigger>
</b:Interaction.Triggers>
</ToggleButton>
</DataTemplate>
</GridViewColumn.CellTemplate>
</GridViewColumn>