🐛 Fix: Implementare DataTemplate ViewModel-View in App.xaml

src/PTRP.App/App.xaml

@@ -1,7 +1,8 @@
 <Application x:Class="PTRP.App.App"
              xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-             xmlns:materialDesign="http://materialdesigninxaml.net/winfx/xaml/themes">
+             xmlns:materialDesign="http://materialdesigninxaml.net/winfx/xaml/themes"
+             xmlns:converters="clr-namespace:PTRP.App.Converters">
     <Application.Resources>
         <ResourceDictionary>
             <ResourceDictionary.MergedDictionaries>
@@ -14,10 +15,24 @@
 
             <!-- Application Resources -->
             <BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter" />
+            <BooleanToVisibilityConverter x:Key="BoolToVisibilityConverter" />
+
+            <!-- Custom Converters (Issue #94) -->
+            <converters:NullToVisibilityConverter x:Key="NullToVisibilityConverter" />
+            <converters:ProjectStateToColorConverter x:Key="ProjectStateToColorConverter" />
 
             <BitmapImage x:Key="AppIcon" UriSource="/favicon.ico" />
 
-            <!-- ViewModel to View DataTemplates will be registered by NavigationService at runtime -->
+            <!-- ========================================
+                 ViewModel to View Mapping
+                 Issue #94: View resolution via ViewLocator (code-behind)
+
+                 DataTemplates removed because Views require DI in constructors.
+                 ViewLocator (src/PTRP.App/Infrastructure/ViewLocator.cs) handles 
+                 View instantiation with proper dependency injection.
+
+                 Mapping managed in MainWindow.xaml.cs via PropertyChanged event.
+                 ======================================== -->
 
         </ResourceDictionary>
     </Application.Resources>

src/PTRP.App/App.xaml.cs

@@ -9,9 +9,11 @@
 using PTRP.Data;
 using PTRP.Data.Repositories;
 using PTRP.Data.Repositories.Interfaces;
+using PTRP.App.Infrastructure;
 using PTRP.App.Views.Patients;
 using PTRP.App.Views.Educators;
 using PTRP.App.Views.Projects;
+using PTRP.App.Views.Sync;
 using System.IO;
 using System.Windows;
 
@@ -112,6 +114,9 @@ private void ConfigureServices(ServiceCollection services)
             services.AddSingleton<INavigationService, NavigationService>();  // Issue #46: Navigation Service
             services.AddScoped<IConfigurationService, ConfigurationService>(); // Issue #49: Configuration Service
 
+            // Registra ViewLocator (Issue #94: DI-based View resolution)
+            services.AddSingleton<ViewLocator>();
+
             // Registra i ViewModels
             services.AddSingleton<MainViewModel>();  // Singleton per condividere stato app
             // TODO: Issue #49 - Uncomment when implemented
@@ -125,11 +130,12 @@ private void ConfigureServices(ServiceCollection services)
             services.AddTransient<SyncViewModel>();        // Issue #52: Sync ViewModel
             services.AddTransient<ConflictResolutionViewModel>(); // Issue #52: Conflict Resolution ViewModel
 
-            // Registra le Views
+            // Registra le Views (Issue #94: Views with DI-based constructors)
             services.AddScoped<MainWindow>();
             services.AddScoped<PatientListView>();  // Issue #51/#74: Patient List View
             services.AddScoped<EducatorListView>();  // Issue #63: Educator List View
             services.AddScoped<ProjectListView>();  // Issue #64: Project List View
+            services.AddScoped<SyncView>();         // Issue #52: Sync View
         }
 
         /// <summary>

src/PTRP.App/Converters/NullToVisibilityConverter.cs

@@ -3,51 +3,35 @@
 using System.Windows;
 using System.Windows.Data;
 
-namespace PTRP.App.Converters
+namespace PTRP.App.Converters;
+
+/// <summary>
+/// Converts null to Visibility.Collapsed and non-null to Visibility.Visible.
+/// Used throughout the app for conditional visibility based on object presence.
+/// </summary>
+public class NullToVisibilityConverter : IValueConverter
 {
     /// <summary>
-    /// Converts null/empty values to Visibility enum.
-    /// Used to hide UI elements when data is not available.
+    /// When true, inverts the logic: null = Visible, non-null = Collapsed
     /// </summary>
-    public class NullToVisibilityConverter : IValueConverter
-    {
-        /// <summary>
-        /// Converts null/empty value to Visibility.
-        /// </summary>
-        /// <param name="value">Value to check (object, string, etc.)</param>
-        /// <param name="targetType">Target type (Visibility)</param>
-        /// <param name="parameter">Optional parameter ("Invert" to reverse logic)</param>
-        /// <param name="culture">Culture info</param>
-        /// <returns>Visibility.Visible if value is not null/empty, Visibility.Collapsed otherwise</returns>
-        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
-        {
-            bool isNull = value == null;
-
-            // Check for empty strings
-            if (!isNull && value is string str)
-            {
-                isNull = string.IsNullOrWhiteSpace(str);
-            }
+    public bool Invert { get; set; } = false;
 
-            // Check for parameter to invert logic
-            bool invert = parameter is string param && param.Equals("Invert", StringComparison.OrdinalIgnoreCase);
+    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+    {
+        bool isNull = value == null;
 
-            if (invert)
-            {
-                return isNull ? Visibility.Visible : Visibility.Collapsed;
-            }
-            else
-            {
-                return isNull ? Visibility.Collapsed : Visibility.Visible;
-            }
+        if (Invert)
+        {
+            return isNull ? Visibility.Visible : Visibility.Collapsed;
         }
-
-        /// <summary>
-        /// Not implemented (one-way binding only).
-        /// </summary>
-        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        else
         {
-            throw new NotImplementedException("NullToVisibilityConverter is one-way only.");
+            return isNull ? Visibility.Collapsed : Visibility.Visible;
         }
     }
+
+    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+    {
+        throw new NotImplementedException("NullToVisibilityConverter does not support ConvertBack");
+    }
 }

src/PTRP.App/Converters/ProjectStateToColorConverter.cs

@@ -2,45 +2,33 @@
 using System.Globalization;
 using System.Windows.Data;
 using System.Windows.Media;
+using PTRP.Models.Enums;
 
-namespace PTRP.App.Converters
+namespace PTRP.App.Converters;
+
+/// <summary>
+/// Converts TherapyProjectState enum to a Color brush for UI display.
+/// Used in ProjectListView for status badges.
+/// </summary>
+public class ProjectStateToColorConverter : IValueConverter
 {
-    /// <summary>
-    /// Converts project state string to color brush for badge display.
-    /// Used in PatientListView DataGrid to show colored status badges.
-    /// </summary>
-    public class ProjectStateToColorConverter : IValueConverter
+    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
     {
-        /// <summary>
-        /// Converts project state to color brush.
-        /// </summary>
-        /// <param name="value">Project state string (Active, Suspended, Completed, Deceased, None)</param>
-        /// <param name="targetType">Target type (Brush)</param>
-        /// <param name="parameter">Optional parameter</param>
-        /// <param name="culture">Culture info</param>
-        /// <returns>SolidColorBrush for the badge background</returns>
-        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
-        {
-            if (value is not string state)
-                return new SolidColorBrush(Colors.Gray);
-
-            return state switch
-            {
-                "Active" => new SolidColorBrush(Color.FromRgb(76, 175, 80)),      // Material Green 500
-                "Suspended" => new SolidColorBrush(Color.FromRgb(255, 193, 7)),   // Material Amber 500
-                "Completed" => new SolidColorBrush(Color.FromRgb(158, 158, 158)), // Material Grey 500
-                "Deceased" => new SolidColorBrush(Color.FromRgb(244, 67, 54)),    // Material Red 500
-                "None" => new SolidColorBrush(Color.FromRgb(189, 189, 189)),      // Material Grey 400
-                _ => new SolidColorBrush(Colors.Gray)
-            };
-        }
+        if (value is not TherapyProjectState status)
+            return Brushes.Gray;
 
-        /// <summary>
-        /// Not implemented (one-way binding only).
-        /// </summary>
-        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        return status switch
         {
-            throw new NotImplementedException("ProjectStateToColorConverter is one-way only.");
-        }
+            TherapyProjectState.Active => new SolidColorBrush(Color.FromRgb(40, 167, 69)),      // Green #28A745
+            TherapyProjectState.Suspended => new SolidColorBrush(Color.FromRgb(255, 193, 7)),   // Yellow #FFC107
+            TherapyProjectState.Completed => new SolidColorBrush(Color.FromRgb(0, 123, 255)),   // Blue #007BFF
+            TherapyProjectState.Deceased => new SolidColorBrush(Color.FromRgb(108, 117, 125)),  // Gray #6C757D
+            _ => Brushes.Gray
+        };
+    }
+
+    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+    {
+        throw new NotImplementedException("ProjectStateToColorConverter does not support ConvertBack");
     }
 }

src/PTRP.App/Infrastructure/ViewLocator.cs

@@ -0,0 +1,73 @@
+using System;
+using System.Windows.Controls;
+using Microsoft.Extensions.DependencyInjection;
+using PTRP.App.Views.Educators;
+using PTRP.App.Views.Patients;
+using PTRP.App.Views.Projects;
+using PTRP.App.Views.Setup;
+using PTRP.App.Views.Sync;
+using PTRP.ViewModels;
+using PTRP.ViewModels.Educators;
+using PTRP.ViewModels.Patients;
+using PTRP.ViewModels.Projects;
+
+namespace PTRP.App.Infrastructure;
+
+/// <summary>
+/// Locates and instantiates Views for ViewModels using Dependency Injection.
+/// Replaces DataTemplate approach when Views require constructor parameters.
+/// Issue #94: Enables MVVM navigation with DI-based View constructors.
+/// </summary>
+public class ViewLocator
+{
+    private readonly IServiceProvider _serviceProvider;
+
+    public ViewLocator(IServiceProvider serviceProvider)
+    {
+        _serviceProvider = serviceProvider ?? throw new ArgumentNullException(nameof(serviceProvider));
+    }
+
+    /// <summary>
+    /// Creates a View instance for the given ViewModel, resolving dependencies via DI.
+    /// Sets the ViewModel as the View's DataContext.
+    /// </summary>
+    /// <param name="viewModel">The ViewModel instance</param>
+    /// <returns>A UserControl instance with DataContext set to the ViewModel, or null if no matching View found</returns>
+    public UserControl? CreateViewForViewModel(object? viewModel)
+    {
+        if (viewModel == null)
+            return null;
+
+        UserControl? view = viewModel switch
+        {
+            // First Run / Setup
+            FirstRunViewModel => new FirstRunView(),
+
+            // Patients Module (requires IServiceProvider in constructor)
+            PatientListViewModel => _serviceProvider.GetRequiredService<PatientListView>(),
+
+            // Educators Module (requires IServiceProvider in constructor)
+            EducatorListViewModel => _serviceProvider.GetRequiredService<EducatorListView>(),
+
+            // Projects Module (requires IServiceProvider in constructor)
+            ProjectListViewModel => _serviceProvider.GetRequiredService<ProjectListView>(),
+
+            // ProjectFormView is created manually with specific patient context,
+            // so it's not navigated to directly - it's opened in dialogs
+            ProjectFormViewModel => new ProjectFormView(),
+
+            // Sync Module (requires IServiceProvider in constructor)
+            SyncViewModel => _serviceProvider.GetRequiredService<SyncView>(),
+
+            // Unknown ViewModel - return null
+            _ => null
+        };
+
+        if (view != null)
+        {
+            view.DataContext = viewModel;
+        }
+
+        return view;
+    }
+}

src/PTRP.App/MainWindow.xaml

@@ -340,9 +340,9 @@
                 </Grid>
             </Border>
 
-            <!-- DYNAMIC CONTENT AREA -->
-            <ContentControl Grid.Row="1" 
-                          Content="{Binding CurrentViewModel}"
+            <!-- DYNAMIC CONTENT AREA - ViewLocator managed in code-behind (Issue #94) -->
+            <ContentControl x:Name="ContentArea"
+                          Grid.Row="1" 
                           Margin="0"/>
 
             <!-- SNACKBAR for notifications (MessageQueue set in code-behind) -->

src/PTRP.App/MainWindow.xaml.cs

@@ -1,6 +1,9 @@
+using System;
+using System.ComponentModel;
+using System.Windows;
 using MaterialDesignThemes.Wpf;
+using PTRP.App.Infrastructure;
 using PTRP.ViewModels;
-using System.Windows;
 
 namespace PTRP.App;
 
@@ -12,19 +15,22 @@ namespace PTRP.App;
 /// 1. Collegamento del ViewModel (binding)
 /// 2. Setup MessageQueue per Snackbar
 /// 3. Gestione eventi notifica dal ViewModel
+/// 4. Risoluzione View tramite ViewLocator (Issue #94)
 /// </summary>
 public partial class MainWindow : Window
 {
     private readonly MainViewModel _viewModel;
+    private readonly ViewLocator _viewLocator;
 
     /// <summary>
-    /// Costruttore - riceve il ViewModel via Dependency Injection
+    /// Costruttore - riceve il ViewModel e ViewLocator via Dependency Injection
     /// </summary>
-    public MainWindow(MainViewModel viewModel)
+    public MainWindow(MainViewModel viewModel, ViewLocator viewLocator)
     {
         InitializeComponent();
 
         _viewModel = viewModel;
+        _viewLocator = viewLocator;
 
         // Imposta il ViewModel come DataContext
         DataContext = _viewModel;
@@ -34,6 +40,33 @@ public MainWindow(MainViewModel viewModel)
 
         // Subscribe to notification events
         _viewModel.NotificationRequested += OnNotificationRequested;
+
+        // Subscribe to CurrentViewModel changes to resolve Views via ViewLocator
+        _viewModel.PropertyChanged += OnViewModelPropertyChanged;
+    }
+
+    /// <summary>
+    /// Intercetta i cambiamenti di CurrentViewModel e risolve la View tramite ViewLocator.
+    /// Issue #94: Permette Views con costruttori DI invece di DataTemplate statici.
+    /// </summary>
+    private void OnViewModelPropertyChanged(object? sender, PropertyChangedEventArgs e)
+    {
+        if (e.PropertyName == nameof(MainViewModel.CurrentViewModel))
+        {
+            // Risolvi la View per il ViewModel corrente tramite ViewLocator
+            var view = _viewLocator.CreateViewForViewModel(_viewModel.CurrentViewModel);
+
+            // Imposta la View nel ContentControl
+            if (view != null)
+            {
+                ContentArea.Content = view;
+            }
+            else
+            {
+                // ViewModel sconosciuto o non implementato - mostra placeholder
+                ContentArea.Content = null;
+            }
+        }
     }
 
     /// <summary>
@@ -77,6 +110,7 @@ private void OnNotificationRequested(object? sender, NotificationEventArgs e)
     protected override void OnClosed(EventArgs e)
     {
         _viewModel.NotificationRequested -= OnNotificationRequested;
+        _viewModel.PropertyChanged -= OnViewModelPropertyChanged;
         base.OnClosed(e);
     }
 }