Fixed Items in a HierarchicalDataTemplate

Question

I need to create a TreeView in WPF that looks something like this:

• Admins (Group)
  • Users (Fixed Node)
    • Alice Adams (User)
    • Bob Brown (User)
  • Permissions (Fixed Node)
    • Delete (Permission)
    • Update (Permission)
• Guests (Group)
  • Users (Fixed Node)
    • Charlie Clarke (User)
  • Permissions (Fixed Node)
    • View (Permission)

I have a list of Groups, and each group has 3 properties:

• Name (string)
• Users (List)
• Permissions (List)

Displaying just the Users or Permissions is easy:

        <TreeView ItemsSource="{Binding Groups}">
            <TreeView.ItemTemplate>
                <HierarchicalDataTemplate ItemsSource="{Binding Users}">
                    <TextBlock Text="{Binding GroupName}" />

                    <HierarchicalDataTemplate.ItemTemplate>
                        <DataTemplate>
                            <TextBlock Text="{Binding UserName}" />
                        </DataTemplate>
                    </HierarchicalDataTemplate.ItemTemplate>
                </HierarchicalDataTemplate>
            </TreeView.ItemTemplate>
        </TreeView>

But I need to add 2 nodes (Users and Permissions) which expand to display the 2 list.

Any suggestions greatly appreciated...

Answer 1

You could use a MultiBinding with a converter to do something like this:

<HierarchicalDataTemplate DataType="{x:Type local:GroupClass}">
        <HierarchicalDataTemplate.ItemsSource>
            <MultiBinding Converter="{StaticResource converter-that-returns-lists-as-is}">
                <Binding Path="Users"/>
                <Binding Path="Permissions"/>
            </MultiBinding>
        </HierarchicalDataTemplate.ItemsSource>
        <TextBlock Text="{Binding Path=Name}"/>
    </HierarchicalDataTemplate>

    <HierarchicalDataTemplate x:Key="IEnumerable[UserClass]" ItemsSource="{Binding Path=.}">
        <TextBlock Text="Users"/>
    </HierarchicalDataTemplate>

    <DataTemplate DataType="{x:Type local:UserClass}">
        <TextBlock Text="{Binding Path=Name}"/>
    </DataTemplate>

    <HierarchicalDataTemplate x:Key="IEnumerable[PermissionClass]" ItemsSource="{Binding Path=.}">
        <TextBlock Text="Permissions"/>
    </HierarchicalDataTemplate>

    <DataTemplate DataType="{x:Type local:PermissionClass}">
        <TextBlock Text="{Binding Path=Name}"/>
    </DataTemplate>

The converter would just give back the lists unmodified as IEnumerable<T>.