AncestorBinding & ItemsControlBinding

These markup extensions provide relative binding based on ancestor type. If you are familiar with WPF, they are very similar to {RelativeSource Mode=FindAncestor}. They are typically used from inside a DataTemplate to access elements outside of said data-template which is not normally accessible (eg: through ElementName binding). The common usage is to access the parent data-context from inside the ItemsControl.ItemTemplate.

Remarks

Both of the markup extensions are available for all non-Windows UWP platforms as well as all WinUI 3 platforms.

ItemsControlBinding

This markup extension provides a binding to the closest parent ItemsControl. This markup can be used to access the parent ItemsControl from inside of the ItemTemplate.

Tip

This is a shortcut for {utu:AncestorBinding AncestorType=ItemsControl}.

Properties

see the Properties section in AncestorBinding.

Usage

public class ExampleModel
{
    public int[] Items { get; } = new[] { 1, 2, 3 };
    public string SomeText { get; } = "Lorem Ipsum";
}

<!-- Include the following XAML namespace to use the samples below -->
xmlns:utu="using:Uno.Toolkit.UI"
...

<!-- Assuming the DataContext is set to an instance of ExampleModel -->
<ListView ItemsSource="{Binding Items}">
    <ListView.ItemTemplate>
        <DataTemplate>
            <StackPanel>
                <TextBlock>Current item DataContext: <Run Text="{Binding}" /></TextBlock>
                <TextBlock>Current parent(ExampleModel) DataContext:
                    <Run Text="{utu:ItemsControlBinding Path=DataContext.SomeText}" />
                </TextBlock>
            <StackPanel>
        </DataTemplate>
    </ListView.ItemTemplate>
</ListView>

AncestorBinding

This markup extension provides a means to bind to an ancestor of a specific type.

Properties

Property	Type	Description
AncestorType	Type	Type of ancestor to bind from.
Path	string	Binding path from the ancestor.
Converter	IValueConverter	Converter object that is called by the binding engine to modify the data as it is passed between the source and target, or vice versa.
ConverterParameter	object	Parameter that can be used in the Converter logic.
ConverterLanguage	string	value that names the language to pass to any converter specified by the Converter property.

Usage

public class ExampleModel
{
    public int[] Items { get; } = new[] { 1, 2, 3 };
    public string SomeText { get; } = "Lorem Ipsum";
}

<!-- Include the following XAML namespace to use the samples below -->
xmlns:utu="using:Uno.Toolkit.UI"
...

<!-- Assuming the DataContext is set to an instance of ExampleModel -->
<Page Tag="From Page">
    <StackPanel>
        <TextBlock Text="From DataContext:" />
        <TextBlock Text="{Binding SomeText}" />

        <ListView ItemsSource="{Binding Items}" Tag="From ListView">
            <ListView.ItemTemplate>
                <DataTemplate>
                    <StackPanel>
                        <TextBlock Text="Current item DataContext:" />
                        <TextBlock FontWeight="Bold" Text="{Binding}" />

                        <TextBlock Text="Current parent (ExampleModel) DataContext:" />
                        <TextBlock FontWeight="Bold" Text="{utu:ItemsControlBinding Path=DataContext.SomeText}" />

                        <TextBlock Text="Accessing property of a parent ListView:" />
                        <TextBlock FontWeight="Bold" Text="{utu:ItemsControlBinding Path=Tag}" />

                        <TextBlock Text="Accessing property of a Page:" />
                        <TextBlock FontWeight="Bold" Text="{utu:AncestorBinding AncestorType=Page, Path=Tag}" />
                    </StackPanel>
                </DataTemplate>
            </ListView.ItemTemplate>
        </ListView>
    </Grid>
</Page>