Silverlight 2.0 - databinding a domain object to a UserControl - silverlight

Question

I am starting out with Silverlight. I want to display a list of messages on the UI, but the databinding isn't working for me.
I have a Message class:
public class Message
{
public string Text { get; set; }
...
}
I have the message display Silverlight User control with a Message dependency property:
public partial class MessageDisplay : UserControl
{
public static readonly DependencyProperty MessageProperty =
DependencyProperty.Register("Message", typeof(Message),
typeof(MessageDisplay), null);
public MessageDisplay()
{
InitializeComponent();
}
public Message Message
{
get
{
return (Message)this.GetValue(MessageProperty);
}
set
{
this.SetValue(MessageProperty, value);
this.DisplayMessage(value);
}
}
private void DisplayMessage(Message message)
{
if (message == null)
{
this.MessageDisplayText.Text = string.Empty;
}
else
{
this.MessageDisplayText.Text = message.Text;
}
}
}
}
Then in the main control xaml I have
<ListBox x:Name="MessagesList" Style="{StaticResource MessagesListBoxStyle}">
<ListBox.ItemTemplate>
<DataTemplate>
<Silverbox:MessageDisplay Message="{Binding}"></Silverbox:MessageDisplay>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox
And I bind in the control.xaml.cs code:
this.MessagesList.SelectedIndex = -1;
this.MessagesList.ItemsSource = this.messages;
Databinding gives no error, and it seems that there are the right number of items in the list, but a breakpoint in MessageDisplay's Message property settor is never hit, and the message is never displayed properly.
What have I missed?

Answer 1

Your Message property is probably being set by the databinding which is bypassing your actual Message property (not the dependency one). To fix this add a PropertyChangedCallback on that property.
public static readonly DependencyProperty MessageProperty =
DependencyProperty.Register("Message", typeof(Message), typeof(MessageDisplay),
new PropertyMetadata(
new PropertyChangedCallback(MessageDisplay.MessagePropertyChanged));
public static void MessagePropertyChanged(DependencyObject obj, DependecyPropertyChangedEventArgs e)
{
((MessageDisplay)obj).Message = (Message)e.NewValue;
}
PropertyMetadata
PropertyChangedCallback