Merge pull request #24 from giard-alexandre/fix/filtering-crash

Fix/filtering crash

samples/SampleApp/ViewModels/MainWindowViewModel.cs

@@ -1,21 +1,32 @@
 using System;
 using System.Collections.ObjectModel;
+using System.Reactive.Linq;
 
 using Bogus;
 using Bogus.DataSets;
 
+using DynamicData;
 using DynamicData.Binding;
 
 using DynamicTreeDataGrid;
 using DynamicTreeDataGrid.Columns;
 
+using ReactiveUI;
+
 namespace SampleApp.ViewModels;
 
-public class MainWindowViewModel : ViewModelBase {
+public class MainWindowViewModel : ReactiveObject {
 	public DynamicFlatTreeDataGridSource<Person, int> DataSource { get; set; }
 
+	private string? _filterText;
+	public string? FilterText
+	{
+		get => _filterText;
+		set => this.RaiseAndSetIfChanged(ref _filterText, value);
+	}
+
 	public MainWindowViewModel() {
-		//Set the randomizer seed if you wish to generate repeatable data sets.
+		//Set the randomizer seed to generate repeatable data sets.
 		Randomizer.Seed = new Random(8675309);
 		var data = new ObservableCollection<Person>(new Faker<Person>()
 			.RuleFor(person => person.Id, faker => faker.IndexFaker)
@@ -27,7 +38,14 @@ public MainWindowViewModel() {
 			.RuleFor(person => person.IsChecked, faker => faker.Random.Bool())
 			.Generate(300)).ToObservableChangeSet(person => person.Id);
 
-		DataSource = new DynamicFlatTreeDataGridSource<Person, int>(data) {
+
+		var searchFilter = this.WhenValueChanged(t => t.FilterText)
+			.Throttle(TimeSpan.FromMilliseconds(500))
+			.Select(BuildSearchFilter);
+
+		var filteredData = data.Filter(searchFilter);
+
+		DataSource = new DynamicFlatTreeDataGridSource<Person, int>(filteredData) {
 			Columns = {
 				new DynamicTextColumn<Person, int>("Id", "Id", person => person.Id),
 				new DynamicTextColumn<Person, string>("Name", "Name", person => person.Name),
@@ -40,6 +58,13 @@ public MainWindowViewModel() {
 			},
 		};
 	}
+
+	private static Func<Person, bool> BuildSearchFilter(string? text) {
+		if (string.IsNullOrEmpty(text))
+			return _ => true;
+
+		return t => t.Name.Contains(text, StringComparison.OrdinalIgnoreCase);
+	}
 }
 
 public record Person {

samples/SampleApp/Views/MainWindow.axaml

@@ -17,6 +17,10 @@
 	</Design.DataContext>
 
 	<DockPanel>
+		<StackPanel Orientation="Horizontal" DockPanel.Dock="Top">
+			<Label Target="FilterTextBox">Filter Name: </Label>
+			<TextBox Name="FilterTextBox" Text="{Binding FilterText}" Width="200" />
+		</StackPanel>
 		<dynamicTreeDataGrid:DynamicTreeDataGrid Source="{Binding DataSource}">
 			<TreeDataGrid.Resources>
 				<DataTemplate x:Key="HeightCell" DataType="{x:Type viewModels:Person}">

src/DynamicTreeDataGrid/DynamicFlatTreeDataGridSource.cs

@@ -48,6 +48,7 @@ public DynamicFlatTreeDataGridSource(IObservable<IChangeSet<TModel, TModelKey>>
         FilteredCount = filteredChanges.Count();
 
         var disposable = filteredChanges.Sort(_sort) // Use SortAndBind?
+	        .DeferUntilLoaded()
             .Bind(out _items)
             .DisposeMany()
             .Subscribe();