How to programmatically bind a (dependency) property of a control that's inside a DataTemplate?

Question

The TextBlock resides in a DataTemplate, thus I can\'t refer to it by its name. So how do I bind its (e.g.) Text property programmatically

Answer 1

You can get TextBlock using VisualTreeHelper. This method will get you all TextBlockes present in Visual tree of listBoxItem:

public IEnumerable<T> FindVisualChildren<T>(DependencyObject depObj)
            where T : DependencyObject
{
   if( depObj != null )
   {
       for( int i = 0; i < VisualTreeHelper.GetChildrenCount( depObj ); i++ )
       {
          DependencyObject child = VisualTreeHelper.GetChild( depObj, i );
          if( child != null && child is T )
          {
              yield return (T)child;
          }

          foreach( T childOfChild in FindVisualChildren<T>( child ) )
          {
             yield return childOfChild;
          }
       }
    }
}

Usage :

TextBlock textBlock = FindVisualChildren<TextBlock>(listBoxItem)
                       .FirstOrDefault();

But I would still suggest to do the binding in XAML instead of doing it in code behind.

In case ItemSource is ObservableCollection<MyModel> and MyModel contains property Name, it can be done in XAML like this:

<DataTemplate>
   <StackPanel Orientation="Horizontal">
      <TextBlock Text="{Binding Name}"/>
   </StackPanel>
 </DataTemplate>

Since DataContext of ListBoxItem will be MyModel, hence you can bind directly to Name property like mentioned above.