Binding to a Dependency Property inside UserControl XAML

Question

I want to reuse a control, but one of the scenarios requires a context menu and the others do not. Here's my attempt.

public partial class RP8Grid : UserControl { public bool UseContextMenu { get { return (bool)GetValue(UseContextMenuProperty); } set { SetValue(UseContextMenuProperty, value); } } // Using a DependencyProperty as the backing store for UseContextMenu. This enables animation, styling, binding, etc... public static readonly DependencyProperty UseContextMenuProperty = DependencyProperty.Register("UseContextMenu", typeof(bool), typeof(RP8Grid), new PropertyMetadata(false)); public RP8Grid() { InitializeComponent(); } }

And in the XAML to use the Property:

<ctls:RP8Grid UseContextMenu="False"/>

Now the part I cannot square away, how do I access UseContextMenu inside the UserControl? I Have tried the following:

<DataGrid> <DataGrid.ContextMenu> <ContextMenu IsEnabled="{Binding UseContextMenu,RelativeSource={RelativeSource AncestorType=UserControl, Mode=FindAncestor}}"> </DataGrid.ContextMenu> </DataGrid>

with results:

Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.UserControl', AncestorLevel='1'

You are right, I think I hit propa instead of propdp. My first implementation. RelativeSource, then up thru the ancestor chain? — markokstate
– markokstate, Commented Jul 13, 2017 at 17:50
<ContextMenu IsEnabled={Binding UseContextMenu, RelativeSource={RelativeSource AncestorType=UserControl}}" /> — 15ee8f99-57ff-4f92-890c-b56153
– 15ee8f99-57ff-4f92-890c-b56153, Commented Jul 13, 2017 at 17:52
Right, ContextMenus are out of the visual tree; my bad. I was able to do this with a binding proxy (that answer illustrates doing something else with one). However, disabling a contextmenu is problematic: It still opens, but with all its items disabled -- and it doesn't close properly. It might be better to give your DataGrid a Style which assigns it the context menu when that property is true. — 15ee8f99-57ff-4f92-890c-b56153
– 15ee8f99-57ff-4f92-890c-b56153, Commented Jul 13, 2017 at 19:22

15ee8f99-57ff-4f92-890c-b56153 · Accepted Answer · 2021-07-29 12:46:13Z

If what you want is just to get rid of the ContextMenu at times, this will work:

<DataGrid > <DataGrid.Style> <Style TargetType="DataGrid" BasedOn="{StaticResource {x:Type DataGrid}}"> <Style.Triggers> <DataTrigger Binding="{Binding UseContextMenu, RelativeSource={RelativeSource AncestorType=UserControl}}" Value="True" > <Setter Property="ContextMenu"> <Setter.Value> <ContextMenu > <MenuItem Header="Test Item" /> <MenuItem Header="Test Item" /> <MenuItem Header="Test Item" /> <MenuItem Header="Test Item" /> </ContextMenu> </Setter.Value> </Setter> </DataTrigger> </Style.Triggers> </Style> </DataGrid.Style> </DataGrid>

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