Using bindings in DataTrigger condition

Question

Let\'s say I have the following simple classes:

public class Person
{
    public int Id { get; set; }
    public string Name { get; set; }
}

public class P         


        

Answer 1

You can't use a binding on the Value property, but you can get around this by using a MultiBinding and an IMultiValueConverter. I would define my Trigger in a Style in e.g. the Window.Resources, which would give something like this:

<Window.Resources>
    <local:SomeMultiConverter x:Key="someMultiConverter" />
    <Style x:Key="someStyle" TargetType="StackPanel">
        <Setter Property="StackPanel.Background" Value="Red" />
        <Style.Triggers>
            <DataTrigger Value="True">
                <DataTrigger.Binding>
                    <MultiBinding Converter="{StaticResource someMultiConverter}">
                        <Binding Path="Id"></Binding>
                        <Binding ElementName="Foo" Path="DataContext.ActiveId"></Binding>
                    </MultiBinding>
                </DataTrigger.Binding>
                <Setter Property="StackPanel.Background" Value="Green" />
            </DataTrigger>
        </Style.Triggers>
    </Style> 
</Window.Resources>
<Grid x:Name="Foo">
    <StackPanel DataContext="{Binding CurrentPerson}" Style="{StaticResource someStyle}" >
        <TextBlock Text="{Binding Id}" />
        <TextBlock Text="{Binding Name}" />
    </StackPanel>
</Grid>

See this link for an example on MultiBinding and IMultiValueConverter. They're fairly easy to write.