Implement functionality for added controls in TreeViewPage.xaml.cs

samples/ControlCatalog/Pages/ListBoxPage.xaml.cs

@@ -36,7 +36,7 @@ namespace ControlCatalog.Pages
 
                 RemoveItemCommand = ReactiveCommand.Create(() =>
                 {
-                    foreach (string selectedItem in listBox.SelectedItems)
+                    foreach (string selectedItem in _listBox.SelectedItems)
                     {
                         Items.Remove(selectedItem);
                     }

samples/ControlCatalog/Pages/TreeViewPage.xaml.cs

@@ -1,8 +1,9 @@
-using System.Collections;
-using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.Linq;
+using System.Reactive;
 using Avalonia.Controls;
 using Avalonia.Markup.Xaml;
+using ReactiveUI;
 
 namespace ControlCatalog.Pages
 {
@@ -10,8 +11,8 @@ namespace ControlCatalog.Pages
     {
         public TreeViewPage()
         {
-            this.InitializeComponent();
-            DataContext = new Node().Children;
+            InitializeComponent();
+            DataContext = new PageViewModel(this.Find<TreeView>("treeView"));
         }
 
         private void InitializeComponent()
@@ -19,22 +20,96 @@ namespace ControlCatalog.Pages
             AvaloniaXamlLoader.Load(this);
         }
 
-        public class Node
+        private class PageViewModel : ReactiveObject
         {
-            private IList<Node> _children;
+            private readonly TreeView _treeView;
+            private SelectionMode _selectionMode;
+
+            public PageViewModel(TreeView treeView)
+            {
+                _treeView = treeView;
+
+                Node root = new Node();
+                Items = root.Children;
+
+                AddItemCommand = ReactiveCommand.Create(() =>
+                {
+                    Node selectedItem = _treeView.SelectedItems.Count > 0 ? (Node)_treeView.SelectedItems[0] : root;
+                    selectedItem.AddNewItem();
+                });
+
+                RemoveItemCommand = ReactiveCommand.Create(() =>
+                {
+                    foreach (Node selectedItem in _treeView.SelectedItems)
+                    {
+                        RecursiveRemove(Items, selectedItem);
+                    }
+
+                    _treeView.SelectedItems.Clear();
+
+                    bool RecursiveRemove(ObservableCollection<Node> items, Node selectedItem)
+                    {
+                        if (items.Remove(selectedItem))
+                        {
+                            return true;
+                        }
+
+                        foreach (Node item in items)
+                        {
+                            if (item.AreChildrenInitialized && RecursiveRemove(item.Children, selectedItem))
+                            {
+                                return true;
+                            }
+                        }
+
+                        return false;
+                    }
+                });
+            }
+
+            public ObservableCollection<Node> Items { get; }
+
+            public ReactiveCommand<Unit, Unit> AddItemCommand { get; }
+
+            public ReactiveCommand<Unit, Unit> RemoveItemCommand { get; }
+
+            public SelectionMode SelectionMode
+            {
+                get => _selectionMode;
+                set
+                {
+                    _treeView.SelectedItems.Clear();
+                    this.RaiseAndSetIfChanged(ref _selectionMode, value);
+                }
+            }
+        }
+
+        private class Node
+        {
+            private int _counter;
+            private ObservableCollection<Node> _children;
+
             public string Header { get; private set; }
-            public IList<Node> Children
+
+            public bool AreChildrenInitialized => _children != null;
+
+            public ObservableCollection<Node> Children
             {
                 get
                 {
                     if (_children == null)
                     {
-                        _children = Enumerable.Range(1, 10).Select(i => new Node() {Header = $"Item {i}"})
-                            .ToArray();
+                        _children = new ObservableCollection<Node>(Enumerable.Range(1, 10).Select(i => CreateNewNode()));
                     }
                     return _children;
                 }
             }
+
+            public void AddNewItem() => Children.Add(CreateNewNode());
+
+            public override string ToString() => Header;
+
+            private Node CreateNewNode() => new Node {Header = $"Item {_counter++}"};
         }
     }
 }