In WPF, how do I get a command in a Control Template to bind to a property in a parent?

Question

I am relatively new to WPF and sometimes it makes my head explode. However, I do like the power behind it, especially when used with the MVVM model.

I have a ControlTemplate that contains a Button. I use that ControlTemplate inside of a custom control. I want to add a property on the custom control that will bind to the command property of the Button inside the ControlTemplate. Basically, it is a ComboBox with a Button to the right of it to allow a user to pop up a search dialog. Since this control could appear on a usercontrol multiple times, I need to be able to potentially bind each control to a different command (search products, search customers, etc).

However, I have been unable to figure out how to do this.

Here is some sample XAML:

<Style TargetType="{x:Type m:SelectionFieldControl}">
    <Setter Property="LookupTemplate" Value="{StaticResource LookupTemplate}" />
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type m:SelectionFieldControl}">
                <Border BorderThickness="{TemplateBinding Border.BorderThickness}" 
                            Padding="{TemplateBinding Control.Padding}" 
                            BorderBrush="{TemplateBinding Border.BorderBrush}" 
                            Background="{TemplateBinding Panel.Background}" 
                            SnapsToDevicePixels="True"
                            Focusable="False">
                    <Grid>
                        <Grid.ColumnDefinitions>
                            <ColumnDefinition Width="Auto" MinWidth="0" 
                                              SharedSizeGroup="{Binding LabelShareSizeGroupName, 
                                                                        RelativeSource={RelativeSource FindAncestor, 
                                                                               AncestorType={x:Type m:BaseFieldControl}}}" />
                            <ColumnDefinition Width="1*" />
                            <ColumnDefinition Width="Auto" 
                                              SharedSizeGroup="{Binding WidgetsShareSizeGroupName, 
                                                                        RelativeSource={RelativeSource FindAncestor, 
                                                                               AncestorType={x:Type m:BaseFieldControl}}}" />
                        </Grid.ColumnDefinitions>

                        <!-- Customized Value Part -->
                        <ComboBox x:Name="PART_Value" 
                                  Grid.Column="1"
                                  Margin="4,2,0,1" 
                                  SelectedValue="{Binding Path=SelectionField.Value, 
                                                          RelativeSource={RelativeSource FindAncestor, 
                                                                                         AncestorType={x:Type m:SelectionFieldControl}}}"

                                  IsEnabled="{Binding Field.IsNotReadOnly,
                                                      RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type m:SelectionFieldControl}}}"
                                  Visibility="{Binding Field.IsInEditMode, Converter={StaticResource TrueToVisible},
                                                       RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type m:SelectionFieldControl}}}"

                                  FontFamily="{StaticResource FontFamily_Default}" FontSize="11px">
                            <ComboBox.ItemsPanel>
                                <ItemsPanelTemplate>
                                    <VirtualizingStackPanel IsVirtualizing="True" 
                                                            VirtualizationMode="Recycling"/>
                                </ItemsPanelTemplate>
                            </ComboBox.ItemsPanel>
                        </ComboBox>

                        <StackPanel Grid.Column="2" 
                                    Orientation="Horizontal" 
                                    Name="PART_Extra"
                                    Focusable="False">

                            <ContentControl Name="PART_LookupContent"
                                            Template="{Binding LookupTemplate, 
                                                               RelativeSource={RelativeSource FindAncestor, 
                                                                                              AncestorType={x:Type m:SelectionFieldControl}}}" 
                                            Focusable="False"/>
                        </StackPanel>
                    </Grid>
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

I thought I could get it to work by doing something like this:

<Button Command="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type SelectionFieldControl}}, Path=ShowSearchCommand}" Margin="2" />

but it does not work.

Any help would be greatly appreciated.

score 1 · Answer 1 · answered May 20 '10 at 19:46

Doh!

That does work. The problem was that my dependency property didnt use UIPropertyMetadata for the property Meta data when registering the property.

public ICommand ShowSearchCommand { get { return (ICommand)GetValue(ShowSearchCommandProperty); } set { SetValue(ShowSearchCommandProperty, value); } }

    public static readonly DependencyProperty ShowSearchCommandProperty =
        DependencyProperty.Register("ShowSearchCommand", typeof(ICommand),
            typeof(SelectionFieldControl),
            new UIPropertyMetadata(OnShowSearchCommandChanged));

    static void OnShowSearchCommandChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
    {

    }

In WPF, how do I get a command in a Control Template to bind to a property in a parent?

1 Answers1