WPF DataBound treeview expand / collapse - wpf

Question

I'm just trying to find a way to control the expand / collapse of the TreeView nodes through the object they're bound to. The object has an IsExpanded property, and I want to use that to show the TreeView node itself expanded or collapsed based on that property.
Here's my code:
C#:
public partial class Window2 : Window
{
public Window2()
{
InitializeComponent();
this.DataContext = new List<Parent>() { Base.GetParent("Parent 1"), Base.GetParent("Parent 2") };
}
}
public class Base
{
public string Name { get; set; }
public bool IsExpanded { get; set; }
public static Parent GetParent(string name)
{
Parent p = new Parent() { Name = name };
p.Children.Add(new Child() { Name = "Child 1", GrandChildren = new ObservableCollection<GrandChild>() { new GrandChild() { Name = "Grandchild 1" } } });
p.Children.Add(new Child() { Name = "Child 2", GrandChildren = new ObservableCollection<GrandChild>() { new GrandChild() { Name = "Grandchild 1" } } });
p.Children.Add(new Child() { Name = "Child 3", GrandChildren = new ObservableCollection<GrandChild>() { new GrandChild() { Name = "Grandchild 1" } } });
return p;
}
}
public class Parent : Base
{
public ObservableCollection<Child> Children { get; set; }
public Parent()
{
this.Children = new ObservableCollection<Child>();
}
}
public class Child : Base
{
public ObservableCollection<GrandChild> GrandChildren { get; set; }
public Child()
{
this.GrandChildren = new ObservableCollection<GrandChild>();
}
}
public class GrandChild : Base
{
}
XAML:
<Window x:Class="HeterogeneousExperimentExplorer.Window2"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:HeterogeneousTree"
Title="Window2" Height="300" Width="300">
<Window.Resources>
<HierarchicalDataTemplate DataType="{x:Type local:Parent}" ItemsSource="{Binding Children}">
<TextBlock Text="{Binding Name}" />
<HierarchicalDataTemplate.ItemTemplate>
<HierarchicalDataTemplate DataType="{x:Type local:Parent}" ItemsSource="{Binding GrandChildren}">
<TextBlock Text="{Binding Name}" />
<HierarchicalDataTemplate.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Name}" />
</DataTemplate>
</HierarchicalDataTemplate.ItemTemplate>
</HierarchicalDataTemplate>
</HierarchicalDataTemplate.ItemTemplate>
</HierarchicalDataTemplate>
</Window.Resources>
<Grid>
<TreeView ItemsSource="{Binding}" />
</Grid>
</Window>

Answer 1

Came up with solution:
<Style TargetType="{x:Type TreeViewItem}">
<Setter Property="IsExpanded" Value="{Binding IsNodeExpanded}"/>
</Style>
So the style gets the object bound to the TreeViewItem and looks at its IsNodeExpanded attribute and it assigns that value to the TreeViewItem.IsExpanded property. If you add Mode=TwoWay, they'll notify each other (TreeViewItem will tell the object when it has been expanded).