Question

I have a basic WinRT XAML UserControl with a single dependency property as implemented below. The user control is apparently only constructed design-time when used in another Page or UserControl. The text “Hello world” is not rendered when I work in the designer with the user control itself. How can I make the designer initialize the user control with data also in this case?

XAML:

<UserControl
    x:Class="GTWin8.Ui.SimpleBinding"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:GTWin8.Ui"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    d:DesignHeight="300"
    d:DesignWidth="400"
    x:Name="ThisControl">

    <Grid Background="Black">
        <TextBlock Text="{Binding Path=Message, ElementName=ThisControl}" 
                   HorizontalAlignment="Left" Margin="10,10,0,0" 
                   TextWrapping="Wrap" VerticalAlignment="Top" Height="280" Width="380"/>
    </Grid>
</UserControl>

Code-behind:

public sealed partial class SimpleBinding : UserControl
{
    public static DependencyProperty MessageProperty = DependencyProperty.Register(
           "Message", typeof(String), typeof(SimpleBinding), new PropertyMetadata(null));

    public String Message
    {
        get { return (String)GetValue(MessageProperty); }
        set { SetValue(MessageProperty, value); }
    }

    public SimpleBinding()
    {
        this.InitializeComponent();
        Message = "Hello world";
    }
}

Answer 1

Well, a simpler method is declarative invocation.

<UserControl>

    <d:Page.DataContext>
        <sample:FakeViewModel />
    </d:Page.DataContext>

    <Grid>
        <!-- your bind/content -->
    </Grid>

</UserControl>

I use this in all my projects because it delivers design time data without interfering with my runtime experience. More: http://blog.jerrynixon.com/2012/06/windows-8-15-more-reasons-why-i-choose.html