Question

I’ve got a WrapPanel from the Silverlight Toolkit in a WP7 application. In my codebehind I add my own usercontrols to this wrappanel. Each usercontrol is a square that displays information about a flight.

        <ScrollViewer x:Name="MyScrollViewer" HorizontalScrollBarVisibility="Auto" VerticalScrollBarVisibility="Auto" Height="307" VerticalAlignment="Bottom">
            <toolkit:WrapPanel x:Name="MonitoredWrapPanel" Margin="10,0,0,0" MinWidth="200" Width="{Binding ElementName=MyScrollViewer, Path=ViewportWidth}">
                <toolkit:ContextMenuService.ContextMenu>
                    <toolkit:ContextMenu x:Name="FlightContextMenuInGrid">
                        <toolkit:MenuItem Header="Stop monitoring flight" Click="MenuItem_Click" Tag="{Binding Path=FlightId}" />
                    </toolkit:ContextMenu>
                </toolkit:ContextMenuService.ContextMenu>
            </toolkit:WrapPanel>
        </ScrollViewer>

And the codebehind;

        foreach (var flight in Cache.MonitoredCombinedFlights)
        {
            FlightSquare square = new FlightSquare();
            square.DataContext = flight;
            square.Margin = new Thickness(10, 5, 10, 5);
            this.MonitoredWrapPanel.Children.Add(square);
        }

My problem is that the MenuItem (for the ContextMenu) doesn’t bind to the FlightId property of the DataContext for my User Control, instead it just binds to itself.

How can I get the MenuItem to understand which FlightSquare it is on?

Answer 1

Apparently the ContextMenu has a different DataContext. Binding in each square has nothing to do with the WrapPanel here and you will have to manually set the binding object for the ContextMenu in the code-behind.

So to say, here is a snippet that shows how you can bind to a property in code-behind (exactly what you need to do):

Binding b = new Binding();
b.Source = ObjectToBindTo;
b.Path = new PropertyPath("PropertyToBindTo");

menu.SetBinding(DependencyPropertyToBind, b);

That being said, there is one more problem in your case. The ContextMenu is inside a WrapPanel – it is tied to it and not to the square. Therefore, you might change the way you are using the ContextMenu to be inside the square instance rather than the common container.