Added new result awaiting and setting ViewModel navigation

MvvmCross/Core/MvxSetup.cs

@@ -12,6 +12,7 @@
 using MvvmCross.Navigation;
 using MvvmCross.Plugin;
 using MvvmCross.ViewModels;
+using MvvmCross.ViewModels.Result;
 using MvvmCross.Views;
 
 namespace MvvmCross.Core;
@@ -154,6 +155,8 @@ public virtual void InitializeSecondary()
             var app = InitializeMvxApplication(_iocProvider);
             SetupLog?.Log(LogLevel.Trace, "Setup: NavigationService");
             InitializeNavigationService(_iocProvider);
+            SetupLog?.Log(LogLevel.Trace, "Setup: ResultViewModelManager");
+            InitializeResultViewModelManager(_iocProvider);
             SetupLog?.Log(LogLevel.Trace, "Setup: ViewModelTypeFinder start");
             InitializeViewModelTypeFinder(_iocProvider);
             SetupLog?.Log(LogLevel.Trace, "Setup: ViewsContainer start");
@@ -345,6 +348,7 @@ protected virtual void RegisterDefaultSetupDependencies(IMvxIoCProvider iocProvi
         iocProvider.LazyConstructAndRegisterSingleton<IMvxViewModelLoader, MvxViewModelLoader>();
         iocProvider.LazyConstructAndRegisterSingleton<IMvxNavigationService, IMvxViewModelLoader, IMvxViewDispatcher, IMvxIoCProvider>(
             (loader, dispatcher, p) => new MvxNavigationService(loader, dispatcher, p));
+        iocProvider.LazyConstructAndRegisterSingleton<IMvxResultViewModelManager, MvxResultViewModelManager>();
         iocProvider.RegisterSingleton(() => new MvxViewModelByNameLookup());
         iocProvider.LazyConstructAndRegisterSingleton<IMvxViewModelByNameLookup, MvxViewModelByNameLookup>(
             nameLookup => nameLookup);
@@ -577,6 +581,20 @@ protected virtual IEnumerable<Assembly> GetBootstrapOwningAssemblies()
         return GetViewAssemblies().Distinct();
     }
 
+    protected virtual IMvxResultViewModelManager? InitializeResultViewModelManager(IMvxIoCProvider iocProvider)
+    {
+        ValidateArguments(iocProvider);
+
+        return CreateResultViewModelManager(iocProvider);
+    }
+
+    protected virtual IMvxResultViewModelManager? CreateResultViewModelManager(IMvxIoCProvider iocProvider)
+    {
+        ValidateArguments(iocProvider);
+
+        return iocProvider.Resolve<IMvxResultViewModelManager>();
+    }
+
     protected abstract IMvxNameMapping CreateViewToViewModelNaming();
 
     protected virtual IMvxViewModelByNameLookup? CreateViewModelByNameLookup(IMvxIoCProvider iocProvider)

MvvmCross/Navigation/MvxNavigationExtensions.cs

@@ -4,6 +4,7 @@
 #nullable enable
 
 using MvvmCross.ViewModels;
+using MvvmCross.ViewModels.Result;
 
 namespace MvvmCross.Navigation;
 
@@ -37,4 +38,75 @@ public static Task Navigate<TParameter>(this IMvxNavigationService navigationSer
     {
         return navigationService.Navigate(path.ToString(), param, presentationBundle, cancellationToken);
     }
+
+    /// <summary>
+    /// Navigate from a Result Awaiting ViewModel to a Result Setting ViewModel determined by its type
+    /// </summary>
+    /// <param name="navigationService">Navigation service</param>
+    /// <param name="fromViewModel">Result Awaiting ViewModel</param>
+    /// <param name="presentationBundle">(optional) presentation bundle</param>
+    /// <param name="cancellationToken">(optional) CancellationToken to cancel the navigation</param>
+    /// <typeparam name="TViewModel">Type of <see cref="IMvxResultSettingViewModel{TResult}"/></typeparam>
+    /// <typeparam name="TResult">Result awaited by Result Awaiting ViewModel and set by Result Setting ViewModel</typeparam>
+    /// <returns>Boolean indicating successful navigation</returns>
+    public static async Task<bool> NavigateRegisteringToResult<TViewModel, TResult>(
+        this IMvxNavigationService navigationService,
+        IMvxResultAwaitingViewModel<TResult> fromViewModel,
+        IMvxBundle? presentationBundle = null,
+        CancellationToken cancellationToken = default)
+        where TViewModel : IMvxResultSettingViewModel<TResult>
+    {
+        bool navigated = await navigationService.Navigate(typeof(TViewModel), presentationBundle, cancellationToken);
+        if (navigated)
+            fromViewModel.RegisterToResult();
+        return navigated;
+    }
+
+    /// <summary>
+    /// Navigate from a Result Awaiting ViewModel to a Result Setting ViewModel determined by its type, with parameter
+    /// </summary>
+    /// <param name="navigationService">Navigation service</param>
+    /// <param name="fromViewModel">Result Awaiting ViewModel</param>
+    /// <param name="parameter">ViewModel parameter</param>
+    /// <param name="presentationBundle">(optional) presentation bundle</param>
+    /// <param name="cancellationToken">(optional) CancellationToken to cancel the navigation</param>
+    /// <typeparam name="TViewModel">Type of <see cref="IMvxResultSettingViewModel{TResult}"/> and <see cref="IMvxViewModel{TParameter}"/></typeparam>
+    /// <typeparam name="TResult">Result awaited by Result Awaiting ViewModel and set by Result Setting ViewModel</typeparam>
+    /// <returns>Boolean indicating successful navigation</returns>
+    public static async Task<bool> NavigateRegisteringToResult<TViewModel, TParameter, TResult>(
+        this IMvxNavigationService navigationService,
+        IMvxResultAwaitingViewModel<TResult> fromViewModel,
+        TParameter parameter,
+        IMvxBundle? presentationBundle = null,
+        CancellationToken cancellationToken = default)
+        where TViewModel : IMvxResultSettingViewModel<TResult>, IMvxViewModel<TParameter>
+    {
+        bool navigated = await navigationService.Navigate(typeof(TViewModel), parameter, presentationBundle, cancellationToken);
+        if (navigated)
+            fromViewModel.RegisterToResult();
+        return navigated;
+    }
+
+    /// <summary>
+    /// Closes the View attached to the Result Setting ViewModel, with result
+    /// </summary>
+    /// <param name="navigationService">Navigation service</param>
+    /// <param name="viewModel">Result Setting ViewModel to close</param>
+    /// <param name="result">Result set by Result Setting ViewModel</param>
+    /// <param name="cancellationToken">(optional) CancellationToken to cancel the closing</param>
+    /// <typeparam name="TViewModel">Type of <see cref="IMvxResultSettingViewModel{TResult}"/></typeparam>
+    /// <typeparam name="TResult">Result set by Result Setting ViewModel</typeparam>
+    /// <returns></returns>
+    public static async Task<bool> CloseSettingResult<TViewModel, TResult>(
+        this IMvxNavigationService navigationService,
+        TViewModel viewModel,
+        TResult result,
+        CancellationToken cancellationToken = default)
+        where TViewModel : IMvxResultSettingViewModel<TResult>
+    {
+        bool closed = await navigationService.Close(viewModel, cancellationToken);
+        if (closed)
+            viewModel.SetResult(result);
+        return closed;
+    }
 }

MvvmCross/ViewModels/MvxNavigationViewModel.cs

@@ -2,9 +2,9 @@
 // The .NET Foundation licenses this file to you under the MS-PL license.
 // See the LICENSE file in the project root for more information.
 
-using System.Threading.Tasks;
 using Microsoft.Extensions.Logging;
 using MvvmCross.Navigation;
+using MvvmCross.ViewModels.Result;
 
 namespace MvvmCross.ViewModels
 {
@@ -27,8 +27,8 @@ protected MvxNavigationViewModel(ILoggerFactory logFactory, IMvxNavigationServic
         protected virtual ILogger Log => _log ??= LoggerFactory.CreateLogger(GetType().Name);
     }
 
-    public abstract class MvxNavigationViewModel<TParameter> : MvxNavigationViewModel, IMvxViewModel<TParameter>
-        where TParameter : class
+    public abstract class MvxNavigationViewModel<TParameter>
+        : MvxNavigationViewModel, IMvxViewModel<TParameter>
     {
         protected MvxNavigationViewModel(ILoggerFactory logFactory, IMvxNavigationService navigationService)
             : base(logFactory, navigationService)
@@ -37,5 +37,74 @@ protected MvxNavigationViewModel(ILoggerFactory logFactory, IMvxNavigationServic
 
         public abstract void Prepare(TParameter parameter);
     }
+
+    public abstract class MvxNavigationResultAwaitingViewModel<TResult>
+        : MvxNavigationViewModel, IMvxResultAwaitingViewModel<TResult>
+    {
+        protected MvxNavigationResultAwaitingViewModel(ILoggerFactory logFactory, IMvxNavigationService navigationService)
+            : base(logFactory, navigationService)
+        {
+        }
+
+        protected override void ReloadFromBundle(IMvxBundle state)
+        {
+            base.ReloadFromBundle(state);
+            this.ReloadAndRegisterToResult(state);
+        }
+
+        protected override void SaveStateToBundle(IMvxBundle bundle)
+        {
+            base.SaveStateToBundle(bundle);
+            this.SaveRegisterToResult(bundle);
+        }
+
+        public override void ViewDestroy(bool viewFinishing = true)
+        {
+            base.ViewDestroy(viewFinishing);
+
+            if (viewFinishing)
+            {
+                this.UnregisterToResult();
+            }
+        }
+
+        public abstract bool ResultSet(IMvxResultSettingViewModel<TResult> viewModel, TResult result);
+    }
+
+    public abstract class MvxNavigationResultAwaitingViewModel<TParameter, TResult>
+        : MvxNavigationResultAwaitingViewModel<TResult>, IMvxViewModel<TParameter>
+    {
+        protected MvxNavigationResultAwaitingViewModel(ILoggerFactory logFactory, IMvxNavigationService navigationService)
+            : base(logFactory, navigationService)
+        {
+        }
+
+        public abstract void Prepare(TParameter parameter);
+    }
+
+    public abstract class MvxNavigationResultSettingViewModel<TResult>
+        : MvxNavigationViewModel, IMvxResultSettingViewModel<TResult>
+    {
+        protected MvxNavigationResultSettingViewModel(ILoggerFactory logFactory, IMvxNavigationService navigationService)
+            : base(logFactory, navigationService)
+        {
+        }
+
+        public virtual void SetResult(TResult result)
+        {
+            this.SetResult<TResult>(result);
+        }
+    }
+
+    public abstract class MvxNavigationResultSettingViewModel<TParameter, TResult>
+        : MvxNavigationResultSettingViewModel<TResult>, IMvxViewModel<TParameter>
+    {
+        protected MvxNavigationResultSettingViewModel(ILoggerFactory logFactory, IMvxNavigationService navigationService)
+            : base(logFactory, navigationService)
+        {
+        }
+
+        public abstract void Prepare(TParameter parameter);
+    }
 #nullable restore
 }

MvvmCross/ViewModels/Result/IMvxResultAwaitingViewModel.cs

@@ -0,0 +1,32 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MS-PL license.
+// See the LICENSE file in the project root for more information.
+
+namespace MvvmCross.ViewModels.Result;
+
+/// <summary>
+/// Implementing this interface requires to manually register and unregister ViewModel to result:
+/// <code>
+/// protected override void ReloadFromBundle(IMvxBundle state)
+/// {
+///     base.ReloadFromBundle(state);
+///     this.ReloadAndRegisterToResult&lt;<typeparamref name="TResult"/>&gt;(state);
+/// }
+/// protected override void SaveStateToBundle(IMvxBundle bundle)
+/// {
+///     base.SaveStateToBundle(bundle);
+///     this.SaveRegisterToResult&lt;<typeparamref name="TResult"/>&gt;(bundle);
+/// }
+/// public override ViewDestroy(bool viewFinishing = true)
+/// {
+///     base.ViewDestroy();
+///     if (viewFinishing)
+///         this.UnregisterToResult&lt;<typeparamref name="TResult"/>&gt;();
+/// }
+/// </code>
+/// </summary>
+/// <typeparam name="TResult"></typeparam>
+public interface IMvxResultAwaitingViewModel<TResult> : IMvxViewModel
+{
+    bool ResultSet(IMvxResultSettingViewModel<TResult> viewModel, TResult result);
+}

MvvmCross/ViewModels/Result/IMvxResultSettingViewModel.cs

@@ -0,0 +1,10 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MS-PL license.
+// See the LICENSE file in the project root for more information.
+
+namespace MvvmCross.ViewModels.Result;
+
+public interface IMvxResultSettingViewModel<in TResult> : IMvxViewModel
+{
+    void SetResult(TResult result);
+}

MvvmCross/ViewModels/Result/IMvxResultViewModelManager.cs

@@ -0,0 +1,16 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MS-PL license.
+// See the LICENSE file in the project root for more information.
+
+namespace MvvmCross.ViewModels.Result;
+
+public interface IMvxResultViewModelManager
+{
+    void RegisterToResult<TResult>(IMvxResultAwaitingViewModel<TResult> viewModel);
+
+    bool UnregisterToResult<TResult>(IMvxResultAwaitingViewModel<TResult> viewModel);
+
+    bool IsRegistered<TResult>(IMvxResultAwaitingViewModel<TResult> viewModel);
+
+    void SetResult<TResult>(IMvxResultSettingViewModel<TResult> viewModel, TResult result);
+}