HierarchicalDataTemplate and HeaderedItemsControl with ControlTemplate fails to show nested data...

Question

I can get this pattern to work with Menu and TreeView but I must be missing something when I make an attempt with HeaderedItemsControl:

<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:sys="clr-namespace:System;assembly=mscorlib" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" >
<Page.Resources>

    <HierarchicalDataTemplate x:Key="MenuItemTemplate" ItemsSource="{Binding XPath=foo}">
        <AccessText Text="{Binding XPath=@a}" />
    </HierarchicalDataTemplate>

    <Style TargetType="HeaderedItemsControl">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type HeaderedItemsControl}">
                    <StackPanel>
                        <ContentPresenter ContentSource="Header"/>
                        <ItemsPresenter Margin="10,0,0,0" />
                    </StackPanel>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

    <XmlDataProvider x:Key="RootXml" XPath="/root/foo">
        <x:XData>
            <root xmlns="">
                <foo a="one">
                    <foo a="two" b="wow, two" />
                    <foo a="three" b="wow, three" />
                    <foo a="four" b="wow, four" />
                </foo>
                <foo a="one again">
                    <foo a="two others" b="wow, two others" />
                    <foo a="three the hard way" b="wow, three again" />
                </foo>
            </root>
        </x:XData>
    </XmlDataProvider>

</Page.Resources>

<StackPanel>
    <HeaderedItemsControl
        Header="My Foo List"
        ItemTemplate="{Binding Source={StaticResource MenuItemTemplate}}"
        ItemsSource="{Binding Source={StaticResource RootXml}}">
    </HeaderedItemsControl>
</StackPanel>
</Page>

In XamlPadX, this shows:

My foo list
    one
    one again

Do I need to do something with the ControlTemplate to get the data to display correctly? Or do I need a more elaborate (or an additional) HierarchicalDataTemplate? Also: how do we show the foo/@b data?

Answer 1

This seems to be the deal:

<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:sys="clr-namespace:System;assembly=mscorlib" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" >
<Page.Resources>

    <XmlDataProvider x:Key="RootXml" XPath="/root/foo">
        <x:XData>
            <root xmlns="">
                <foo a="one" b="test1">
                    <foo a="two" b="wow, two" />
                    <foo a="three" b="wow, three" />
                    <foo a="four" b="wow, four" />
                </foo>
                <foo a="one again" b="test2">
                    <foo a="two others" b="wow, two others" />
                    <foo a="three the hard way" b="wow, three again" />
                </foo>
            </root>
        </x:XData>
    </XmlDataProvider>

    <Style TargetType="HeaderedItemsControl">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type HeaderedItemsControl}">
                    <StackPanel>
                        <ContentPresenter ContentSource="Header"/>
                        <ItemsPresenter Margin="10,0,0,0" />
                    </StackPanel>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

    <HierarchicalDataTemplate x:Key="NestedFooItemTemplate">
        <AccessText Text="{Binding XPath=@b}" />
    </HierarchicalDataTemplate>

    <HierarchicalDataTemplate x:Key="FooItemTemplate">
        <StackPanel>
            <AccessText Text="{Binding XPath=@a}" />
            <HeaderedItemsControl
                Header="My Nest"
                ItemTemplate="{Binding Source={StaticResource NestedFooItemTemplate}}"
                ItemsSource="{Binding XPath=./foo}"
                Margin="10,0,0,0" />
        </StackPanel>
    </HierarchicalDataTemplate>

</Page.Resources>

<StackPanel>
    <HeaderedItemsControl
        Header="My Foo List"
        ItemTemplate="{Binding Source={StaticResource FooItemTemplate}}"
        ItemsSource="{Binding Source={StaticResource RootXml}}">
    </HeaderedItemsControl>
</StackPanel>
</Page>

Answer 2

HierarchicalDataTemplate is for tree views which have automatic child element expansion. In your case you can simply use a normal DataTemplate.