Binding to ItemsPresenter property

Question

I have the following XAML:

<ItemsControl ItemsSource="{Binding...}" > <ItemsControl.Template> <ControlTemplate> <ItemsPresenter x:Name="testGrid"/> </ControlTemplate> </ItemsControl.Template> <!--Use the ItemsPanel property to specify a custom UniformGrid that holds the laid out items.--> <ItemsControl.ItemsPanel> <ItemsPanelTemplate> <tools:UniformGridRtL Columns="8" x:Name="testGrid2" /> </ItemsPanelTemplate> </ItemsControl.ItemsPanel> <!--Use the ItemTemplate to set a DataTemplate to define the visualization of the data objects. This DataTemplate specifies that each data object appears RegisterBit appears as a CheckBox bound to RegisterBit properties. It also defines a custom template for the checkbox.--> <ItemsControl.ItemTemplate> <DataTemplate> <CheckBox... /> </DataTemplate> </ItemsControl.ItemTemplate> </ItemsControl> <Label> <Binding ElementName="testGrid2" Path="property_of_UniformGridRtL"/> </Label>

Basically, I have a custom Panel (UniformGridRtL) set as an ItemsPanelTemplate, which will template the ItemsPresenter in the ItemsControl. UniformGridRtL has a property, which I would like to bind to, but ElementName doesn't seem to work in the Label Binding. How can I bind to a property of a generated ItemsControl items host?

Dana Cartwright · Accepted Answer · 2011-01-06 18:48:22Z

The ElementName binding source doesn't work for templated items, even ItemsPanelTemplate ones which usually only have a single templated item. The problem is that because it's a template you could in theory have more than one, so WPF doesn't know which named item to bind to.

As a work-around, try subscribing to the Loaded event of the panel (in this case <tools:UniformGridRtL Loaded="grid_Loaded" .../>), and then set the binding manually in code:

private void grid_Loaded( object sender, RoutedEventArgs e ) { Binding binding = new Binding( "NameOfGridPropertyToBindTo" ); binding.Source = sender; boundLabel.SetBinding( Label.ContentProperty, binding ); }

The code above assumes something like <Label Name="boundLabel"/> for your Label declaration.

Thanks for the work-around... It indeed works, if the binding target is not a template-item too. What happens, if I want to bind to a sibling element in the same ItemsControl ControlTemplate?
If you have a sibling source element, instead of using the sender use (namedItemsControl).Template.FindName() as discussed here: stackoverflow.com/questions/820201/…
Sorry, my comment got cut off - if the target is templated you can use the same strategy with Template.FindName() as well - the code just gets a bit messier. Make sure to still use a Loaded event of some kind though or else you won't have a visual tree yet and FindName will return null.

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