Binding within a UserControl not working (templatebinding to a custom dependency property)

silverlight, windows-phone-7, xaml

Solution

If you want to bind to your "own" dependency property inside a `UserControl` you need to add a `x:Name` to your `UserControl` and use it as the `ElementName` in your binding.

<UserControl x:Name="myControl">
    <!-- omitted namespaces etc. -->
    <Grid x:Name="LayoutRoot">
         <Button x:Name="myButton" 
                 Content="{Binding Data, ElementName=myControl}">        
         </Button>
    </Grid>
</UserControl>

To make the `Template` also work:

Instead of the `TemplateBinding` you need to use the `RelativeSource TemplatedParent` sysntax, because you need to set the `Mode=OneWay` (TemplateBinding uses `Mode=OneTime` for performance reasons by default but in your scenario you need `Mode=OneWay`)

<Style TargetType="Button">
    <Style.Setters>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="Button">
                    <TextBlock Text="{Binding Path=Content, Mode=OneWay, 
                        RelativeSource={RelativeSource TemplatedParent}}" />
                </ControlTemplate>    
            </Setter.Value>
        </Setter>
    </Style.Setters>
</Style>

Problem

I have a user control which I'd like to be used like so: ``` // MainPage.xaml <my:MyControl Data="10" /> <!-- or --> <my:MyControl Data="{Binding SomeData}" /> ``` It's codebind is this: ``` public partial class MyControl : UserControl { public MyControl() { InitializeComponent(); } public const string DataPropertyName = "Data"; public int Data { get { return (int)GetValue(DataProperty); } set { SetValue(DataProperty, value); } } public static readonly DependencyProperty DataProperty = DependencyProperty.Register( DataPropertyName, typeof(int), typeof(MyControl), new PropertyMetadata(10); } ``` It's xaml portion is this: ``` <UserControl> <!-- omitted namespaces etc. --> <Grid x:Name="LayoutRoot"> <Button x:Name="myButton" Content="{Binding Data}"> <Button.Style> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="Button"> <TextBlock Text="{TemplateBinding Content}" /> </ControlTemplate> </Setter.Value> </Button.Style> </Button> </Grid> </UserControl> ``` The crucial line, in usercontrol's xaml part is: ``` <Button x:Name="myButton" Content="{Binding Data}"> ``` I'd like to bind this Button's Content property to the UserControl's property (Data), while still retaining the ability to set values on it from outside (`<my:MyControl Data="10" />`) The problem is, that when I use binding - `<Button x:Name="myButton" Content="{Binding Data}">` - it doesn't work (The templatebinding doesnt pick any values) It works however, if I set the values manually i.e - `<Button x:Name="myButton" Content="12">`

Original source