WPF :当按钮的上下文id改变时，我应该如何改变按钮的样式？

<Window x:Class="WpfApp.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="WPF Button Style" Height="450" Width="800">
    <Window.Resources>
        <Style x:Key="ButtonStyle" TargetType="Button">
            <Setter Property="Background" Value="Green"/>
            <Setter Property="Foreground" Value="White"/>
            <Style.Triggers>
                <DataTrigger Binding="{Binding ContextId}" Value="1">
                    <Setter Property="Background" Value="Red"/>
                </DataTrigger>
                <DataTrigger Binding="{Binding ContextId}" Value="2">
                    <Setter Property="Background" Value="Blue"/>
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </Window.Resources>
    <Grid>
        <Button Content="Button" Style="{StaticResource ButtonStyle}" Width="100" Height="50"/>
    </Grid>
</Window>