uwptreeviewuwp-xamltreeviewitemxbind

UWP TreeView HasUnrealizedChildren when using {x:Bind}


I was reading here: Microsoft Docs: TreeView and I found the property HasUnrealizedChildren that is perfect for my case as I have a TreeStructure that could be very deep and very complex. What I've not understood is how to use it in case of a databinding. In my case I have the same:

                <muxc:TreeView Name="DessertTree"
                                  SelectionMode="Multiple"
                                  ItemsSource="{x:Bind DataSource}">
                <muxc:TreeView.ItemTemplate>
                    <DataTemplate x:DataType="local:Item">
                        <muxc:TreeViewItem
                            ItemsSource="{x:Bind Children}"
                            Content="{x:Bind Name}"/>
                    </DataTemplate>
                </muxc:TreeView.ItemTemplate>
            </muxc:TreeView>

But I do not want to load all the Children, I want to load them only when expanded as explained in the example. But in order to show the Expand gliph I need to set HasUnrealizedChildren for the root items


Solution

  • Here is the trick:

        <DataTemplate
            x:Key="ItemTemplate"
            x:DataType="model:MTreeViewBase"
            x:DefaultBindMode="OneWay">
            <winui:TreeViewItem  IsExpanded="False" ItemsSource="{x:Bind Visits}" HasUnrealizedChildren="{x:Bind Loaded, Converter={StaticResource NotEnumToBooleanConverter}, ConverterParameter=Loaded, Mode=OneWay}">
                <controls1:TreeViewControl Data="{x:Bind}" />
            </winui:TreeViewItem>
        </DataTemplate>
    

    I've used a Converter to change HasUnrealizedChildren to false once the item is loaded