Extend .Bind() to Support TypedBinding (#156)

* Add TypedBindingExtensions

* Update StoryDataTemplate.cs

* Update TypedBindingExtensions.cs

* Update TypedBindingExtensions.cs

* Update TypedBindingExtensions.cs

* Update TypedBindingExtensions.cs

* Add Unit Tests

* `dotnet format`

* Remove duplicate code

* Add Handlers, Change default value of `BindingMode mode = BindingMode.Default`

* Update TypedBindingExtensionsTests.cs

* `dotnet format`

* Update Sample

* Update TypedBindingExtensions.cs

* Remove `string propertyName`

* Update TypedBindingExtensions.cs

* Improve Handlers

* Update Bindings

* Add Handlers Support

* Update TypedBindingExtensionsTests.cs

* Remove Non-required Generic Parameters

* `dotnet format`

* `dotnet format`

* Add `ConfirmReadOnlyTypedBindingWithConversion` Test

* Remove unnecessary `const`

---------

Co-authored-by: Shaun Lawrence <[email protected]>

samples/CommunityToolkit.Maui.Markup.Sample/Pages/NewsDetailPage.cs

@@ -6,7 +6,7 @@ sealed class NewsDetailPage : BaseContentPage<NewsDetailViewModel>
 {
 	public NewsDetailPage(NewsDetailViewModel newsDetailViewModel) : base(newsDetailViewModel, newsDetailViewModel.Title)
 	{
-		this.Bind(TitleProperty, nameof(NewsDetailViewModel.Title));
+		this.Bind(TitleProperty, static (NewsDetailViewModel vm) => vm.Title);
 
 		Content = new FlexLayout
 		{
@@ -17,22 +17,22 @@ public NewsDetailPage(NewsDetailViewModel newsDetailViewModel) : base(newsDetail
 			{
 				new WebView()
 					.Grow(1).AlignSelf(FlexAlignSelf.Stretch)
-					.Bind(WebView.SourceProperty, nameof(NewsDetailViewModel.Uri), BindingMode.OneWay),
+					.Bind(WebView.SourceProperty, static (NewsDetailViewModel vm) => vm.Uri, mode: BindingMode.OneWay),
 
 				new Button()
 					.Text("Launch in Browser \uf35d")
 					.Font(size: 20, family: "FontAwesome")
 					.Basis(50)
 					.Style(AppStyles.ButtonStyle)
-					.Bind(Button.CommandProperty, nameof(NewsDetailViewModel.OpenBrowserCommand), BindingMode.OneWay)
+					.Bind(Button.CommandProperty, static (NewsDetailViewModel vm) => vm.OpenBrowserCommand, mode: BindingMode.OneWay)
 					.SemanticHint("Launches the news article in the devices browser."),
 
 				new Label()
 					.TextCenter()
 					.AlignSelf(FlexAlignSelf.Stretch)
 					.Paddings(bottom: 20)
 					.Style(AppStyles.LabelStyle)
-					.Bind(Label.TextProperty, nameof(NewsDetailViewModel.ScoreDescription), BindingMode.OneWay)
+					.Bind(Label.TextProperty, static (NewsDetailViewModel vm) => vm.ScoreDescription, mode: BindingMode.OneWay)
 					.SemanticHint("Displays the score of the news article."),
 			}
 		};

samples/CommunityToolkit.Maui.Markup.Sample/Pages/NewsPage.cs

@@ -24,11 +24,11 @@ public NewsPage(IDispatcher dispatcher,
 			}.BackgroundColor(Colors.Transparent)
 			 .ItemTemplate(new StoryDataTemplate())
 			 .Invoke(collectionView => collectionView.SelectionChanged += HandleSelectionChanged)
-			 .Bind(CollectionView.ItemsSourceProperty, nameof(NewsViewModel.TopStoryCollection))
+			 .Bind(CollectionView.ItemsSourceProperty, static (NewsViewModel vm) => vm.TopStoryCollection)
 			 .AutomationId("NewsCollectionView")
 
-		}.Bind(RefreshView.IsRefreshingProperty, nameof(NewsViewModel.IsListRefreshing))
-		 .Bind(RefreshView.CommandProperty, nameof(NewsViewModel.PullToRefreshCommand))
+		}.Bind(RefreshView.IsRefreshingProperty, static (NewsViewModel vm) => vm.IsListRefreshing, static (NewsViewModel vm, bool isRefreshing) => vm.IsListRefreshing = isRefreshing)
+		 .Bind(RefreshView.CommandProperty, static (NewsViewModel vm) => vm.PullToRefreshCommand)
 		 .AppThemeColorBinding(RefreshView.RefreshColorProperty, Colors.Black, Colors.LightGray)
 		 .Assign(out refreshView);
 	}

samples/CommunityToolkit.Maui.Markup.Sample/Pages/SettingsPage.cs

@@ -1,60 +1,60 @@
-using Microsoft.Maui.Layouts;
-
-namespace CommunityToolkit.Maui.Markup.Sample.Pages;
-
-sealed class SettingsPage : BaseContentPage<SettingsViewModel>
-{
-	public SettingsPage(SettingsViewModel settingsViewModel) : base(settingsViewModel, "Settings")
-	{
-		Content = new AbsoluteLayout
-		{
-			Children =
-			{
-				new Image().Source("dotnet_bot.png").Opacity(0.25).IsOpaque(false).Aspect(Aspect.AspectFit)
-					.LayoutFlags(AbsoluteLayoutFlags.SizeProportional | AbsoluteLayoutFlags.PositionProportional)
-					.LayoutBounds(0.5, 0.5, 0.5, 0.5)
-					.AutomationIsInAccessibleTree(false),
-
-				new Label()
-					.Text("Top Stories To Fetch")
-					.AppThemeBinding(Label.TextColorProperty,AppStyles.BlackColor, AppStyles.PrimaryTextColorDark)
-					.LayoutFlags(AbsoluteLayoutFlags.XProportional | AbsoluteLayoutFlags.WidthProportional)
-					.LayoutBounds(0, 0, 1, 40)
-					.TextCenterHorizontal()
-					.TextBottom()
-					.Assign(out Label topNewsStoriesToFetchLabel),
-
-				new Entry { Keyboard = Keyboard.Numeric }
-					.BackgroundColor(Colors.White)
-					.Placeholder($"Provide a value between {SettingsService.MinimumStoriesToFetch} and {SettingsService.MaximumStoriesToFetch}", Colors.Grey)
-					.LayoutFlags(AbsoluteLayoutFlags.XProportional | AbsoluteLayoutFlags.WidthProportional)
-					.LayoutBounds(0.5, 45, 0.8, 40)
-					.Behaviors(new NumericValidationBehavior
-					{
-						Flags = ValidationFlags.ValidateOnValueChanged,
-						MinimumValue = SettingsService.MinimumStoriesToFetch,
-						MaximumValue = SettingsService.MaximumStoriesToFetch,
-						ValidStyle = AppStyles.ValidEntryNumericValidationBehaviorStyle,
-						InvalidStyle = AppStyles.InvalidEntryNumericValidationBehaviorStyle,
-					})
-					.Bind(Entry.TextProperty, nameof(SettingsViewModel.NumberOfTopStoriesToFetch))
-					.TextCenter()
-					.SemanticDescription(topNewsStoriesToFetchLabel.Text),
-
-				new Label()
-					.Bind<Label, int, int, string>(
-						Label.TextProperty,
-						binding1: new Binding { Source = SettingsService.MinimumStoriesToFetch },
-						binding2: new Binding { Source = SettingsService.MaximumStoriesToFetch },
-						convert: ((int minimum, int maximum) values) => string.Format(CultureInfo.CurrentUICulture, $"The number must be between {values.minimum} and {values.maximum}."),
-						mode: BindingMode.OneTime)
-					.LayoutFlags(AbsoluteLayoutFlags.XProportional | AbsoluteLayoutFlags.WidthProportional)
-					.LayoutBounds(0, 90, 1, 40)
-					.TextCenter()
-					.AppThemeColorBinding(Label.TextColorProperty,AppStyles.BlackColor, AppStyles.PrimaryTextColorDark)
-					.Font(size: 12, italic: true)
-					.SemanticHint($"The minimum and maximum possible values for the {topNewsStoriesToFetchLabel.Text} field above.")
-			}
-		};
-	}
+using Microsoft.Maui.Layouts;
+
+namespace CommunityToolkit.Maui.Markup.Sample.Pages;
+
+sealed class SettingsPage : BaseContentPage<SettingsViewModel>
+{
+	public SettingsPage(SettingsViewModel settingsViewModel) : base(settingsViewModel, "Settings")
+	{
+		Content = new AbsoluteLayout
+		{
+			Children =
+			{
+				new Image().Source("dotnet_bot.png").Opacity(0.25).IsOpaque(false).Aspect(Aspect.AspectFit)
+					.LayoutFlags(AbsoluteLayoutFlags.SizeProportional | AbsoluteLayoutFlags.PositionProportional)
+					.LayoutBounds(0.5, 0.5, 0.5, 0.5)
+					.AutomationIsInAccessibleTree(false),
+
+				new Label()
+					.Text("Top Stories To Fetch")
+					.AppThemeBinding(Label.TextColorProperty,AppStyles.BlackColor, AppStyles.PrimaryTextColorDark)
+					.LayoutFlags(AbsoluteLayoutFlags.XProportional | AbsoluteLayoutFlags.WidthProportional)
+					.LayoutBounds(0, 0, 1, 40)
+					.TextCenterHorizontal()
+					.TextBottom()
+					.Assign(out Label topNewsStoriesToFetchLabel),
+
+				new Entry { Keyboard = Keyboard.Numeric }
+					.BackgroundColor(Colors.White)
+					.Placeholder($"Provide a value between {SettingsService.MinimumStoriesToFetch} and {SettingsService.MaximumStoriesToFetch}", Colors.Grey)
+					.LayoutFlags(AbsoluteLayoutFlags.XProportional | AbsoluteLayoutFlags.WidthProportional)
+					.LayoutBounds(0.5, 45, 0.8, 40)
+					.Behaviors(new NumericValidationBehavior
+					{
+						Flags = ValidationFlags.ValidateOnValueChanged,
+						MinimumValue = SettingsService.MinimumStoriesToFetch,
+						MaximumValue = SettingsService.MaximumStoriesToFetch,
+						ValidStyle = AppStyles.ValidEntryNumericValidationBehaviorStyle,
+						InvalidStyle = AppStyles.InvalidEntryNumericValidationBehaviorStyle,
+					})
+					.TextCenter()
+					.SemanticDescription(topNewsStoriesToFetchLabel.Text)
+					.Bind(Entry.TextProperty, static (SettingsViewModel vm) => vm.NumberOfTopStoriesToFetch, static (SettingsViewModel vm, int text) => vm.NumberOfTopStoriesToFetch = text),
+
+				new Label()
+					.Bind<Label, int, int, string>(
+						Label.TextProperty,
+						binding1: new Binding { Source = SettingsService.MinimumStoriesToFetch },
+						binding2: new Binding { Source = SettingsService.MaximumStoriesToFetch },
+						convert: ((int minimum, int maximum) values) => string.Format(CultureInfo.CurrentUICulture, $"The number must be between {values.minimum} and {values.maximum}."),
+						mode: BindingMode.OneTime)
+					.LayoutFlags(AbsoluteLayoutFlags.XProportional | AbsoluteLayoutFlags.WidthProportional)
+					.LayoutBounds(0, 90, 1, 40)
+					.TextCenter()
+					.AppThemeColorBinding(Label.TextColorProperty,AppStyles.BlackColor, AppStyles.PrimaryTextColorDark)
+					.Font(size: 12, italic: true)
+					.SemanticHint($"The minimum and maximum possible values for the {topNewsStoriesToFetchLabel.Text} field above.")
+			}
+		};
+	}
 }

samples/CommunityToolkit.Maui.Markup.Sample/Views/News/StoryDataTemplate.cs

@@ -24,13 +24,13 @@ public StoryDataTemplate() : base(CreateGrid)
 				.Row(Row.Title)
 				.Font(size: 16).AppThemeBinding(Label.TextColorProperty, AppStyles.BlackColor, AppStyles.PrimaryTextColorDark)
 				.Top().Padding(10, 0)
-				.Bind(Label.TextProperty, nameof(StoryModel.Title))
+				.Bind(Label.TextProperty, static (StoryModel m) => m.Title, mode: BindingMode.OneTime)
 				.SemanticHint("The title of the news article."),
 
 			new Label().Row(Row.Description)
 				.Font(size: 13).AppThemeBinding(Label.TextColorProperty, AppStyles.SecondaryTextColorLight, AppStyles.SecondaryTextColorDark)
 				.Paddings(10, 0, 10, 5)
-				.Bind(Label.TextProperty, nameof(StoryModel.Description))
+				.Bind(Label.TextProperty, static (StoryModel m) => m.Description, mode: BindingMode.OneTime)
 				.SemanticHint("The description of the news article.")
 		}
 	};

src/CommunityToolkit.Maui.Markup.UnitTests/AbsoluteLayoutExtensionsTests.cs

@@ -1,6 +1,4 @@
 using CommunityToolkit.Maui.Markup.UnitTests.Base;
-using Microsoft.Maui.Controls;
-using Microsoft.Maui.Graphics;
 using Microsoft.Maui.Layouts;
 using NUnit.Framework;
 

src/CommunityToolkit.Maui.Markup.UnitTests/ApplicationTestHelpers.cs

@@ -1,8 +1,4 @@
-using System;
-using Microsoft.Maui.ApplicationModel;
-using Microsoft.Maui.Controls;
-
-namespace CommunityToolkit.Maui.Markup.UnitTests;
+namespace CommunityToolkit.Maui.Markup.UnitTests;
 
 public static class ApplicationTestHelpers
 {

src/CommunityToolkit.Maui.Markup.UnitTests/AutomationPropertiesExtensionsTests.cs

@@ -1,6 +1,4 @@
 using CommunityToolkit.Maui.Markup.UnitTests.Base;
-using Microsoft.Maui;
-using Microsoft.Maui.Controls;
 using NUnit.Framework;
 
 namespace CommunityToolkit.Maui.Markup.UnitTests;

src/CommunityToolkit.Maui.Markup.UnitTests/BindableLayoutExtensionsTests.cs

@@ -1,6 +1,4 @@
-using System;
-using CommunityToolkit.Maui.Markup.UnitTests.Base;
-using Microsoft.Maui.Controls;
+using CommunityToolkit.Maui.Markup.UnitTests.Base;
 using NUnit.Framework;
 
 namespace CommunityToolkit.Maui.Markup.UnitTests;

src/CommunityToolkit.Maui.Markup.UnitTests/BindableObjectExtensionsTests.cs

@@ -1,11 +1,6 @@
-using System;
-using System.Linq;
-using System.Windows.Input;
+using System.Windows.Input;
+using BindableObjectViews;
 using CommunityToolkit.Maui.Markup.UnitTests.Base;
-using CommunityToolkit.Maui.Markup.UnitTests.BindableObjectViews;
-using Microsoft.Maui.ApplicationModel;
-using Microsoft.Maui.Controls;
-using Microsoft.Maui.Graphics;
 using NUnit.Framework;
 
 namespace CommunityToolkit.Maui.Markup.UnitTests
@@ -777,7 +772,7 @@ class ViewModel
 	}
 }
 
-namespace CommunityToolkit.Maui.Markup.UnitTests.BindableObjectViews // This namespace simulates derived controls defined in a separate app, for use in the tests in this file only
+namespace BindableObjectViews // This namespace simulates derived controls defined in a separate app, for use in the tests in this file only
 {
 	class DerivedFromLabel : Label
 	{

src/CommunityToolkit.Maui.Markup.UnitTests/BindableObjectMultiBindExtensionsTests.cs

@@ -1,8 +1,4 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using CommunityToolkit.Maui.Markup.UnitTests.Base;
-using Microsoft.Maui.Controls;
+using CommunityToolkit.Maui.Markup.UnitTests.Base;
 using NUnit.Framework;
 
 namespace CommunityToolkit.Maui.Markup.UnitTests;

src/CommunityToolkit.Maui.Markup.UnitTests/BindingHelpers.cs

@@ -1,9 +1,7 @@
 using System;
-using System.Collections.Generic;
 using System.Globalization;
-using System.Linq;
 using System.Reflection;
-using Microsoft.Maui.Controls;
+using Microsoft.Maui.Controls.Internals;
 using NUnit.Framework;
 
 namespace CommunityToolkit.Maui.Markup.UnitTests;
@@ -46,6 +44,57 @@ internal static void AssertBindingExists<TDest>(
 			bindable, targetProperty, path, mode, assertConverterInstanceIsAnyNotNull, converter, null,
 			stringFormat, source, targetNullValue, fallbackValue, assertConvert);
 
+	internal static void AssertTypedBindingExists<TBindable, TBindingContext, TSource>(
+		TBindable bindable,
+		BindableProperty targetProperty,
+		BindingMode expectedBindingMode,
+		TBindingContext expectedSource,
+		string? expectedFormat = null) where TBindable : BindableObject
+		=> AssertTypedBindingExists<TBindable, TBindingContext, TSource, object?, object?>(
+			bindable, targetProperty, expectedBindingMode, expectedSource, expectedStringFormat: expectedFormat);
+
+	internal static void AssertTypedBindingExists<TBindable, TBindingContext, TSource, TDest>(
+		TBindable bindable,
+		BindableProperty targetProperty,
+		BindingMode expectedBindingMode,
+		TBindingContext expectedSource,
+		Func<TSource?, TDest>? expectedConverter = null,
+		string? expectedFormat = null) where TBindable : BindableObject
+		=> AssertTypedBindingExists<TBindable, TBindingContext, TSource, object?, TDest>(
+			bindable, targetProperty, expectedBindingMode, expectedSource, expectedConverter, expectedStringFormat: expectedFormat);
+
+	internal static void AssertTypedBindingExists<TBindable, TBindingContext, TSource, TParam, TDest>(
+		TBindable bindable,
+		BindableProperty targetProperty,
+		BindingMode expectedBindingMode,
+		TBindingContext expectedSource,
+		Func<TSource?, TDest>? expectedConverter = null,
+		string? expectedStringFormat = null,
+		TDest? expectedTargetNullValue = default,
+		TDest? expectedFallbackValue = default,
+		TParam? expectedConverterParameter = default) where TBindable : BindableObject
+	{
+		var binding = GetTypedBinding(bindable, targetProperty) ?? throw new NullReferenceException();
+		Assert.That(binding, Is.Not.Null);
+
+		Assert.That(binding.Mode, Is.EqualTo(expectedBindingMode));
+
+		var funcConverter = expectedConverter switch
+		{
+			null => null,
+			_ => new FuncConverter<TSource, TDest, TParam>(expectedConverter, null)
+		};
+
+		Assert.That(binding.Converter?.ToString(), Is.EqualTo(funcConverter?.ToString()));
+
+		Assert.That(binding.ConverterParameter, Is.EqualTo(expectedConverterParameter));
+
+		Assert.IsInstanceOf<TBindingContext>(expectedSource);
+		Assert.That(binding.StringFormat, Is.EqualTo(expectedStringFormat));
+		Assert.That(binding.TargetNullValue, Is.EqualTo(expectedTargetNullValue));
+		Assert.That(binding.FallbackValue, Is.EqualTo(expectedFallbackValue));
+	}
+
 	internal static void AssertBindingExists<TDest, TParam>(
 		BindableObject bindable,
 		BindableProperty targetProperty,
@@ -133,39 +182,35 @@ internal static void AssertBindingExists<TDest, TParam>(
 		assertConvert?.Invoke(binding.Converter);
 	}
 
-	internal static Binding? GetBinding(BindableObject bindable, BindableProperty property) => GetBindingBase(bindable, property) as Binding;
+	internal static Binding? GetBinding(BindableObject bindable, BindableProperty property) => GetBindingBase<Binding>(bindable, property);
+
+	internal static TypedBindingBase? GetTypedBinding(BindableObject bindable, BindableProperty property) => GetBindingBase<TypedBindingBase>(bindable, property);
 
-	internal static MultiBinding? GetMultiBinding(BindableObject bindable, BindableProperty property) => GetBindingBase(bindable, property) as MultiBinding;
+	internal static MultiBinding? GetMultiBinding(BindableObject bindable, BindableProperty property) => GetBindingBase<MultiBinding>(bindable, property);
 
 	/// <remarks>
 	/// Note that we are only testing whether the Markup helpers create the correct bindings,
 	/// we are not testing the binding mechanism itself; this is why it is justified to access
 	/// private binding API's here for testing.
 	/// </remarks>
-	internal static BindingBase? GetBindingBase(BindableObject bindable, BindableProperty property)
+	internal static TBinding? GetBindingBase<TBinding>(BindableObject bindable, BindableProperty property) where TBinding : BindingBase
 	{
-		if (getContextMethodInfo is null)
-		{
-			getContextMethodInfo = typeof(BindableObject).GetMethod("GetContext", BindingFlags.NonPublic | BindingFlags.Instance);
-		}
+		getContextMethodInfo ??= typeof(BindableObject).GetMethod("GetContext", BindingFlags.NonPublic | BindingFlags.Instance);
 
 		var context = getContextMethodInfo?.Invoke(bindable, new object[] { property });
 		if (context is null)
 		{
 			return null;
 		}
 
-		if (bindingFieldInfo is null)
-		{
-			bindingFieldInfo = context?.GetType().GetField("Binding");
-		}
+		bindingFieldInfo ??= context?.GetType().GetField("Binding");
 
-		return bindingFieldInfo?.GetValue(context) as BindingBase;
+		return bindingFieldInfo?.GetValue(context) as TBinding;
 	}
 
 	internal static IValueConverter AssertConvert<TValue, TConvertedValue>(this IValueConverter converter, TValue value, object? parameter, TConvertedValue expectedConvertedValue, bool twoWay = false, bool backOnly = false, CultureInfo? culture = null)
 	{
-		Assert.That(converter.Convert(value, typeof(object), parameter, culture), Is.EqualTo(backOnly ? default(TConvertedValue) : expectedConvertedValue));
+		Assert.That(converter.Convert(value, typeof(object), parameter, culture), Is.EqualTo(backOnly ? default : expectedConvertedValue));
 		Assert.That(converter.ConvertBack(expectedConvertedValue, typeof(object), parameter, culture), Is.EqualTo(twoWay || backOnly ? value : default(TValue)));
 		return converter;
 	}
@@ -196,5 +241,5 @@ internal static IMultiValueConverter AssertConvert<TConvertedValue>(this IMultiV
 	}
 
 	internal static IMultiValueConverter AssertConvert<TConvertedValue>(this IMultiValueConverter converter, object[] values, TConvertedValue expectedConvertedValue, bool twoWay = false, bool backOnly = false, CultureInfo? culture = null)
-	=> AssertConvert(converter, values, null, expectedConvertedValue, twoWay, backOnly, culture);
+		=> AssertConvert(converter, values, null, expectedConvertedValue, twoWay, backOnly, culture);
 }

src/CommunityToolkit.Maui.Markup.UnitTests/DefaultBindablePropertiesTests.cs

@@ -1,17 +1,11 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Reflection;
-using System.Text;
-using CommunityToolkit.Maui.Markup.UnitTests.Base;
+using CommunityToolkit.Maui.Markup.UnitTests.Base;
 using NUnit.Framework;
 
 namespace CommunityToolkit.Maui.Markup.UnitTests
 {
 	using CommunityToolkit.Maui.Markup.UnitTests.DefaultBindablePropertiesViews;
 	// These usings are placed here to avoid ambiguities
 	using Microsoft.Maui.Controls;
-	using Microsoft.Maui.Controls.Shapes;
 
 	[TestFixture]
 	class DefaultBindablePropertiesTests : BaseMarkupTestFixture