HierarchicalDataTemplate issue

Question

I need some help with HierarchicalDataTemplate... I am trying to build a TreeView to display some hierarchical data like this:

• RuleSet <- (root) -RuleA
  • RuleB
    • RuleC
    • RuleA .....
  • RuleD

RuleA, ... are derived from the same RuleBase that has a

• Type
• RuleBase[] Rules

RuleSet has

• Name
• List

my code as far as I get:

<TreeView x:Name="ruleSetTree" Margin="0,10,0,0" ItemsSource="{Binding Path=SelectedTypeRuleSet>
            <TreeView.ItemTemplate>
                <HierarchicalDataTemplate  DataType="{x:Type engine:RuleSet}">
                    <HierarchicalDataTemplate.ItemTemplate>
                        <HierarchicalDataTemplate x:Name="leafTemplate"
                              ItemsSource="{Binding Path=Rules}" 
                              DataType="{x:Type engine:RuleBase}">
                            <TextBlock Text="{Binding Path=Name}"/>
                        </HierarchicalDataTemplate>
                    </HierarchicalDataTemplate.ItemTemplate>
                    <TextBlock x:Name="hierarchyItem" Text="{Binding Path=TargetType}"/>
                </HierarchicalDataTemplate>
            </TreeView.ItemTemplate>
 </TreeView>

What I see now is the Name of RuleSet. The toggle button of TreeView is hidden. I deserialize an xml into my RuleSet model to get the data for this TreeView. The RuleSet is filled in correctly...can anyone give a hand please?

Thank you!

Answer 1

There is no ItemsSource specified in the first HierarchicalDataTemplate. Shouldn't you bind it to the List property of your RuleSet ?

Answer 2

Why do you nest another hierarchical data template into the existing one? That may be the mistake. Especially because you didn't specify an ItemSource in your first data template. If all the nodes are of type RuleSet you can do it like this:

<TreeView x:Name="ruleSetTree" Margin="0,10,0,0" ItemsSource="{Binding Path=SelectedTypeRuleSet>
        <TreeView.ItemTemplate>
            <HierarchicalDataTemplate DataType="{x:Type engine:RuleSet}"
                                      ItemsSource="{Binding Path=Rules}">
                <StackPanel>
                    <TextBlock Text="{Binding Path=Name}"/>
                    <TextBlock Text="{Binding Path=TargetType}"/>
                </StackPanel>
            </HierarchicalDataTemplate>
        </TreeView.ItemTemplate>
</TreeView>

UPDATE: Here's an updated version, which should match your requirements. This just works, though, if all the child nodes are of type RuleBase

<UserControl.Resources>
        <HierarchicalDataTemplate x:Key="RuleBaseTemplate"
                                  ItemsSource="{Binding Rules}">
            <TextBlock Text="{Binding Name}"/>
        </HierarchicalDataTemplate>

        <HierarchicalDataTemplate x:Key="RuleSetTemplate" 
                                  ItemsSource="{Binding Rules}" 
                                  ItemTemplate="{StaticResource RuleBaseTemplate}">
            <StackPanel>
                <TextBlock Text="{Binding Name}"/>
                <TextBlock Text="{Binding TargetType}"/>
            </StackPanel>
        </HierarchicalDataTemplate>
</UserControl.Resources>
<!-- rest of the code -->
<TreeView x:Name="ruleSetTree" Margin="0,10,0,0" 
          ItemsSource="{Binding SelectedTypeRuleSet}"
          ItemTemplate="{StaticResource RuleSetTemplate}"/>