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PODependencyProperty binding not happening on initial load
 

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    <p>I'm trying to do something simple -- make a DependencyProperty and then bind to it. However, the getter doesn't appear to fire when I start up the app. (I'm guessing the solution will make me smack my head and go "Doh!", but still. :) )</p> <p>Any ideas?</p> <p>Code-behind code:</p> <pre><code>public static readonly DependencyProperty PriorityProperty = DependencyProperty.Register("Priority", typeof (Priority), typeof (PriorityControl), null); public Priority Priority { get { return (Priority)GetValue(PriorityProperty); } set { SetValue(PriorityProperty, value); } } </code></pre> <p>Control XAML:</p> <pre><code>&lt;ListBox Background="Transparent" BorderThickness="0" ItemsSource="{Binding Path=Priorities}" Name="PriorityList" SelectedItem="{Binding Path=Priority, Mode=TwoWay}"&gt; &lt;ListBox.ItemTemplate&gt; &lt;DataTemplate&gt; &lt;Grid Height="16" Width="16"&gt; &lt;Border BorderBrush="Black" BorderThickness="2" CornerRadius="3" Visibility="{Binding RelativeSource= {RelativeSource Mode=FindAncestor, AncestorType=ListBoxItem}, Path=IsSelected, Converter={StaticResource boolToVisibilityConverter}}" /&gt; &lt;Border CornerRadius="3" Height="12" Width="12"&gt; &lt;Border.Background&gt; &lt;SolidColorBrush Color="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=ListBoxItem}, Path=Content, Converter={StaticResource priorityToColorConverter}}" /&gt; &lt;/Border.Background&gt; &lt;/Border&gt; &lt;/Grid&gt; &lt;/DataTemplate&gt; &lt;/ListBox.ItemTemplate&gt; &lt;ListBox.ItemsPanel&gt; &lt;ItemsPanelTemplate&gt; &lt;StackPanel Orientation="Horizontal"/&gt; &lt;/ItemsPanelTemplate&gt; &lt;/ListBox.ItemsPanel&gt; &lt;/ListBox&gt; </code></pre> <p>Binding statement:</p> <pre><code>&lt;UI:PriorityControl Grid.Column="8" Priority="{Binding Path=Priority}" VerticalAlignment="Center"/&gt; </code></pre> <p>Some other notes:</p> <ul> <li>Binding is in a UserControl</li> <li>UserControl contains the PriorityControl</li> <li>PriorityControl contains the DependencyProperty</li> <li>I've checked that the data the UserControl is getting the appropriate data -- every other binding works.</li> <li>If I change the selection on the PriorityControl via the mouse, everything fires as appropriate. It's just that initial setting of the value that isn't working.</li> <li>Priority is an enum.</li> </ul> <p><strong>EDIT:</strong> I've tried two additional things. First, I made the binding to the value two-way, but that didn't work. Then, I added a property changed callback to the dependency property and made it call OnPropertyChanged, like so:</p> <pre><code>public static readonly DependencyProperty PriorityProperty = DependencyProperty.Register("Priority", typeof (Priority), typeof (PriorityControl), new PropertyMetadata(HandleValueChanged)); private static void HandleValueChanged(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs e) { var npc = dependencyObject as PriorityControl; npc.OnPropertyChanged("Priority"); } </code></pre> <p>That didn't work either. I even tried overriding ApplyTemplate on the control to force a property change notification, but the value is never getting set on initial load. I can change values and see everything fire just fine, but it's that first time that nothing is coming through.</p>
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    1. CO+1 for providing a clear description, code *and* XAML :)
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