Question

I searched the archives for help but I can’t find anything quite specific enough for my particular issue.

I have a TreeView using MVVM to bind data and all seems good. I want to extend the functionality such that I think using a user control for the TreeView items would be good.

Here is the XAML code for the hierarchical data template used by the TreeViewItems:

        <HierarchicalDataTemplate
          DataType="{x:Type vm:SiteViewModel}" 
          ItemsSource="{Binding Children}">
          <StackPanel Orientation="Horizontal">
            <TextBlock Text="{Binding SiteName}"/>
         </StackPanel>
        </HierarchicalDataTemplate>

I want to replace the TextBlock with my user control:

        <uc:MyTextBlock InternalText="{Binding SiteName}"/>

The user control (for now) just contains another TextBlock and has a dependency property called InternalText, i.e.

  <TextBlock Text="{Binding Path=InternalText}" />

and I set the DataContext in the constructor of the user control to itself:

public MyTextBlock ()
{
  InitializeComponent();
  DataContext = this;
}

This isn’t working, but if I just change the template so that it specifies static text it seems to work fine:

        <uc:MyTextBlock InternalText="Some site name"/>

So how do I get the bound data to get passed to the user control? It’s probably something simple but I’m new to WPF so I’ve not worked it out yet.

Thanks!

Answer 1

In the codebehind

public class MyUserControl : UserControl
{
    #region Text
    /// <summary>
    /// The <see cref="DependencyProperty"/> for <see cref="Text"/>.
    /// </summary>
    public static readonly DependencyProperty TextProperty =
        DependencyProperty.Register(
            RunningPropertyName,
            typeof(string),
            typeof(MyUserControl ),
            new UIPropertyMetadata(null));

    /// <summary>
    /// The name of the <see cref="Text"/> <see cref="DependencyProperty"/>.
    /// </summary>
    public const string TextPropertyName = "Text";

    /// <summary>
    /// The text to display
    /// </summary>
    public string Text
    {
        get { return (string)GetValue(TextProperty ); }
        set { SetValue(TextProperty , value); }
    }
    #endregion      
}

In the xaml

<UserControl x:Class="Derp.MyUserControl" 
             x:Name="root"
             SnippingXamlForBrevity="true"

and later…

<TextBlock Text="{Binding Text, ElementName=root}" />