Add starter project for chapter 4

Chapter04/Start/Ch4-MyMediaCollection.sln

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+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.5.33530.505
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "MyMediaCollection", "MyMediaCollection\MyMediaCollection.csproj", "{972D5C0D-86E6-4A2F-A6FD-8D4FE3380707}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|ARM64 = Debug|ARM64
+		Debug|x64 = Debug|x64
+		Debug|x86 = Debug|x86
+		Release|ARM64 = Release|ARM64
+		Release|x64 = Release|x64
+		Release|x86 = Release|x86
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{972D5C0D-86E6-4A2F-A6FD-8D4FE3380707}.Debug|ARM64.ActiveCfg = Debug|ARM64
+		{972D5C0D-86E6-4A2F-A6FD-8D4FE3380707}.Debug|ARM64.Build.0 = Debug|ARM64
+		{972D5C0D-86E6-4A2F-A6FD-8D4FE3380707}.Debug|ARM64.Deploy.0 = Debug|ARM64
+		{972D5C0D-86E6-4A2F-A6FD-8D4FE3380707}.Debug|x64.ActiveCfg = Debug|x64
+		{972D5C0D-86E6-4A2F-A6FD-8D4FE3380707}.Debug|x64.Build.0 = Debug|x64
+		{972D5C0D-86E6-4A2F-A6FD-8D4FE3380707}.Debug|x64.Deploy.0 = Debug|x64
+		{972D5C0D-86E6-4A2F-A6FD-8D4FE3380707}.Debug|x86.ActiveCfg = Debug|x86
+		{972D5C0D-86E6-4A2F-A6FD-8D4FE3380707}.Debug|x86.Build.0 = Debug|x86
+		{972D5C0D-86E6-4A2F-A6FD-8D4FE3380707}.Debug|x86.Deploy.0 = Debug|x86
+		{972D5C0D-86E6-4A2F-A6FD-8D4FE3380707}.Release|ARM64.ActiveCfg = Release|ARM64
+		{972D5C0D-86E6-4A2F-A6FD-8D4FE3380707}.Release|ARM64.Build.0 = Release|ARM64
+		{972D5C0D-86E6-4A2F-A6FD-8D4FE3380707}.Release|ARM64.Deploy.0 = Release|ARM64
+		{972D5C0D-86E6-4A2F-A6FD-8D4FE3380707}.Release|x64.ActiveCfg = Release|x64
+		{972D5C0D-86E6-4A2F-A6FD-8D4FE3380707}.Release|x64.Build.0 = Release|x64
+		{972D5C0D-86E6-4A2F-A6FD-8D4FE3380707}.Release|x64.Deploy.0 = Release|x64
+		{972D5C0D-86E6-4A2F-A6FD-8D4FE3380707}.Release|x86.ActiveCfg = Release|x86
+		{972D5C0D-86E6-4A2F-A6FD-8D4FE3380707}.Release|x86.Build.0 = Release|x86
+		{972D5C0D-86E6-4A2F-A6FD-8D4FE3380707}.Release|x86.Deploy.0 = Release|x86
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {C9277197-C949-4948-80CD-0A685EE6DCBB}
+	EndGlobalSection
+EndGlobal

Chapter04/Start/MyMediaCollection/App.xaml

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+<!-- Copyright (c) Microsoft Corporation and Contributors. -->
+<!-- Licensed under the MIT License. -->
+
+<Application
+    x:Class="MyMediaCollection.App"
+    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:local="using:MyMediaCollection">
+    <Application.Resources>
+        <ResourceDictionary>
+            <ResourceDictionary.MergedDictionaries>
+                <XamlControlsResources xmlns="using:Microsoft.UI.Xaml.Controls" />
+                <!-- Other merged dictionaries here -->
+            </ResourceDictionary.MergedDictionaries>
+            <!-- Other app resources here -->
+        </ResourceDictionary>
+    </Application.Resources>
+</Application>

Chapter04/Start/MyMediaCollection/App.xaml.cs

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+using Microsoft.UI.Xaml;
+using MyMediaCollection.ViewModels;
+
+namespace MyMediaCollection
+{
+    /// <summary>
+    /// Provides application-specific behavior to supplement the default Application class.
+    /// </summary>
+    public partial class App : Application
+    {
+        /// <summary>
+        /// Initializes the singleton application object.  This is the first line of authored code
+        /// executed, and as such is the logical equivalent of main() or WinMain().
+        /// </summary>
+        public App()
+        {
+            this.InitializeComponent();
+        }
+
+        public static MainViewModel ViewModel { get; } = new MainViewModel();
+
+        /// <summary>
+        /// Invoked when the application is launched.
+        /// </summary>
+        /// <param name="args">Details about the launch request and process.</param>
+        protected override void OnLaunched(Microsoft.UI.Xaml.LaunchActivatedEventArgs args)
+        {
+            m_window = new MainWindow();
+            m_window.Activate();
+        }
+
+        private Window m_window;
+    }
+}

Chapter04/Start/MyMediaCollection/Enums/ItemType.cs

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+namespace MyMediaCollection.Enums
+{
+    public enum ItemType
+    {
+        Music,
+        Video,
+        Book
+    }
+}

Chapter04/Start/MyMediaCollection/Enums/LocationType.cs

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+namespace MyMediaCollection.Enums
+{
+    public enum LocationType
+    {
+        InCollection,
+        Loaned
+    }
+}

Chapter04/Start/MyMediaCollection/MainWindow.xaml

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+<!-- Copyright (c) Microsoft Corporation and Contributors. -->
+<!-- Licensed under the MIT License. -->
+
+<Window
+    x:Class="MyMediaCollection.MainWindow"
+    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:local="using:MyMediaCollection"
+    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:model="using:MyMediaCollection.Model"
+    mc:Ignorable="d">
+
+    <Grid>
+        <Grid.RowDefinitions>
+            <RowDefinition Height="Auto"/>
+            <RowDefinition Height="*"/>
+            <RowDefinition Height="Auto"/>
+        </Grid.RowDefinitions>
+
+        <Grid>
+            <Grid.ColumnDefinitions>
+                <ColumnDefinition Width="*"/>
+                <ColumnDefinition Width="Auto"/>
+            </Grid.ColumnDefinitions>
+
+            <TextBlock Text="Media Collection" Margin="4" FontWeight="Bold" VerticalAlignment="Center"/>
+            <StackPanel Grid.Column="1" Orientation="Horizontal" HorizontalAlignment="Right">
+                <TextBlock Text="Media Type:" Margin="4" FontWeight="Bold" VerticalAlignment="Center"/>
+                <ComboBox ItemsSource="{x:Bind ViewModel.Mediums}" SelectedItem="{x:Bind ViewModel.SelectedMedium, Mode=TwoWay}" MinWidth="120" Margin="0,2,6,4"/>
+            </StackPanel>
+        </Grid>
+
+        <ListView Grid.Row="1" ItemsSource="{x:Bind ViewModel.Items}" SelectedItem="{x:Bind ViewModel.SelectedMediaItem, Mode=TwoWay}">
+            <ListView.HeaderTemplate>
+                <DataTemplate>
+                    <Grid>
+                        <Grid.ColumnDefinitions>
+                            <ColumnDefinition Width="100"/>
+                            <ColumnDefinition Width="*"/>
+                        </Grid.ColumnDefinitions>
+
+                        <Border BorderBrush="BlueViolet" BorderThickness="0,0,0,1">
+                            <TextBlock Text="Medium" Margin="5,0,0,0" FontWeight="Bold"/>
+                        </Border>
+                        <Border Grid.Column="1" BorderBrush="BlueViolet" BorderThickness="0,0,0,1">
+                            <TextBlock Text="Title" Margin="5,0,0,0" FontWeight="Bold"/>
+                        </Border>
+                    </Grid>
+                </DataTemplate>
+            </ListView.HeaderTemplate>
+
+            <ListView.ItemTemplate>
+                <DataTemplate x:DataType="model:MediaItem">
+                    <Grid>
+                        <Grid.ColumnDefinitions>
+                            <ColumnDefinition Width="100"/>
+                            <ColumnDefinition Width="*"/>
+                        </Grid.ColumnDefinitions>
+
+                        <TextBlock Text="{x:Bind Path=MediumInfo.Name, Mode=TwoWay}"/>
+                        <TextBlock Grid.Column="1" Text="{x:Bind Path=Name}"/>
+                    </Grid>
+                </DataTemplate>
+            </ListView.ItemTemplate>
+        </ListView>
+
+        <StackPanel Grid.Row="2"
+                    HorizontalAlignment="Right"
+                    Orientation="Horizontal">
+            <Button Command="{x:Bind ViewModel.AddEditCommand}"
+                    Content="Add Item"
+                    Margin="8,8,0,8"/>
+            <Button Command="{x:Bind ViewModel.DeleteCommand}"
+                    Content="Delete Item"
+                    Margin="8"/>
+        </StackPanel>
+    </Grid>
+</Window>

Chapter04/Start/MyMediaCollection/MainWindow.xaml.cs

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+using Microsoft.UI.Xaml;
+using MyMediaCollection.ViewModels;
+
+namespace MyMediaCollection
+{
+    /// <summary>
+    /// An empty window that can be used on its own or navigated to within a Frame.
+    /// </summary>
+    public sealed partial class MainWindow : Window
+    {
+        public MainWindow()
+        {
+            this.InitializeComponent();
+        }
+
+        public MainViewModel ViewModel => App.ViewModel;
+    }
+}

Chapter04/Start/MyMediaCollection/Model/MediaItem.cs

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+using MyMediaCollection.Enums;
+
+namespace MyMediaCollection.Model
+{
+    public class MediaItem
+    {
+        public int Id { get; set; }
+        public string Name { get; set; }
+        public ItemType MediaType { get; set; }
+        public Medium MediumInfo { get; set; }
+        public LocationType Location { get; set; }
+    }
+}

Chapter04/Start/MyMediaCollection/Model/Medium.cs

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+using MyMediaCollection.Enums;
+
+namespace MyMediaCollection.Model
+{
+    public class Medium
+    {
+        public int Id { get; set;  }
+        public string Name { get; set; }
+        public ItemType MediaType { get; set; }
+    }
+}

Chapter04/Start/MyMediaCollection/MyMediaCollection.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>WinExe</OutputType>
+    <TargetFramework>net6.0-windows10.0.19041.0</TargetFramework>
+    <TargetPlatformMinVersion>10.0.17763.0</TargetPlatformMinVersion>
+    <RootNamespace>MyMediaCollection</RootNamespace>
+    <ApplicationManifest>app.manifest</ApplicationManifest>
+    <Platforms>x86;x64;ARM64</Platforms>
+    <RuntimeIdentifiers>win10-x86;win10-x64;win10-arm64</RuntimeIdentifiers>
+    <PublishProfile>win10-$(Platform).pubxml</PublishProfile>
+    <UseWinUI>true</UseWinUI>
+    <EnableMsixTooling>true</EnableMsixTooling>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Content Include="Assets\SplashScreen.scale-200.png" />
+    <Content Include="Assets\LockScreenLogo.scale-200.png" />
+    <Content Include="Assets\Square150x150Logo.scale-200.png" />
+    <Content Include="Assets\Square44x44Logo.scale-200.png" />
+    <Content Include="Assets\Square44x44Logo.targetsize-24_altform-unplated.png" />
+    <Content Include="Assets\StoreLogo.png" />
+    <Content Include="Assets\Wide310x150Logo.scale-200.png" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="CommunityToolkit.Mvvm" Version="8.2.0" />
+    <PackageReference Include="Microsoft.WindowsAppSDK" Version="1.2.221109.1" />
+    <PackageReference Include="Microsoft.Windows.SDK.BuildTools" Version="10.0.22621.755" />
+    <Manifest Include="$(ApplicationManifest)" />
+  </ItemGroup>
+
+  <!-- 
+    Defining the "Msix" ProjectCapability here allows the Single-project MSIX Packaging
+    Tools extension to be activated for this project even if the Windows App SDK Nuget
+    package has not yet been restored.
+  -->
+  <ItemGroup Condition="'$(DisableMsixProjectCapabilityAddedByProject)'!='true' and '$(EnableMsixTooling)'=='true'">
+    <ProjectCapability Include="Msix" />
+  </ItemGroup>
+
+  <!-- 
+    Defining the "HasPackageAndPublishMenuAddedByProject" property here allows the Solution 
+    Explorer "Package and Publish" context menu entry to be enabled for this project even if 
+    the Windows App SDK Nuget package has not yet been restored.
+  -->
+  <PropertyGroup Condition="'$(DisableHasPackageAndPublishMenuAddedByProject)'!='true' and '$(EnableMsixTooling)'=='true'">
+    <HasPackageAndPublishMenu>true</HasPackageAndPublishMenu>
+  </PropertyGroup>
+</Project>

Chapter04/Start/MyMediaCollection/Package.appxmanifest

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+<?xml version="1.0" encoding="utf-8"?>
+
+<Package
+  xmlns="http://schemas.microsoft.com/appx/manifest/foundation/windows10"
+  xmlns:uap="http://schemas.microsoft.com/appx/manifest/uap/windows10"
+  xmlns:rescap="http://schemas.microsoft.com/appx/manifest/foundation/windows10/restrictedcapabilities"
+  IgnorableNamespaces="uap rescap">
+
+  <Identity
+    Name="9457558b-77d0-43f9-b1e4-e6aa9aba05d6"
+    Publisher="CN=alash"
+    Version="1.0.0.0" />
+
+  <Properties>
+    <DisplayName>MyMediaCollection</DisplayName>
+    <PublisherDisplayName>alash</PublisherDisplayName>
+    <Logo>Assets\StoreLogo.png</Logo>
+  </Properties>
+
+  <Dependencies>
+    <TargetDeviceFamily Name="Windows.Universal" MinVersion="10.0.17763.0" MaxVersionTested="10.0.19041.0" />
+    <TargetDeviceFamily Name="Windows.Desktop" MinVersion="10.0.17763.0" MaxVersionTested="10.0.19041.0" />
+  </Dependencies>
+
+  <Resources>
+    <Resource Language="x-generate"/>
+  </Resources>
+
+  <Applications>
+    <Application Id="App"
+      Executable="$targetnametoken$.exe"
+      EntryPoint="$targetentrypoint$">
+      <uap:VisualElements
+        DisplayName="MyMediaCollection"
+        Description="MyMediaCollection"
+        BackgroundColor="transparent"
+        Square150x150Logo="Assets\Square150x150Logo.png"
+        Square44x44Logo="Assets\Square44x44Logo.png">
+        <uap:DefaultTile Wide310x150Logo="Assets\Wide310x150Logo.png" />
+        <uap:SplashScreen Image="Assets\SplashScreen.png" />
+      </uap:VisualElements>
+    </Application>
+  </Applications>
+
+  <Capabilities>
+    <rescap:Capability Name="runFullTrust" />
+  </Capabilities>
+</Package>

Chapter04/Start/MyMediaCollection/Properties/launchSettings.json

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+{
+  "profiles": {
+    "MyMediaCollection (Package)": {
+      "commandName": "MsixPackage"
+    },
+    "MyMediaCollection (Unpackaged)": {
+      "commandName": "Project"
+    }
+  }
+}

Chapter04/Start/MyMediaCollection/ViewModels/BindableBase.cs

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+using System.ComponentModel;
+using System.Runtime.CompilerServices;
+
+namespace MyMediaCollection.ViewModels
+{
+    public class BindableBase : INotifyPropertyChanged
+    {
+        public event PropertyChangedEventHandler PropertyChanged;
+
+        protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
+        {
+            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+        }
+
+        protected bool SetProperty<T>(ref T originalValue, T newValue, [CallerMemberName] string propertyName = null)
+        {
+            if (Equals(originalValue, newValue))
+            {
+                return false;
+            }
+
+            originalValue = newValue;
+            OnPropertyChanged(propertyName);
+
+            return true;
+        }
+    }
+}

Chapter04/Start/MyMediaCollection/ViewModels/MainViewModel.cs

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+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+using MyMediaCollection.Enums;
+using MyMediaCollection.Model;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Windows.Input;
+
+namespace MyMediaCollection.ViewModels
+{
+    public partial class MainViewModel : ObservableObject
+    {
+        [ObservableProperty]
+        private string selectedMedium;
+        [ObservableProperty]
+        private ObservableCollection<MediaItem> items;
+        [ObservableProperty]
+        private IList<string> mediums;
+
+        [ObservableProperty]
+        [NotifyCanExecuteChangedFor(nameof(DeleteCommand))]
+        private MediaItem selectedMediaItem;
+
+        private ObservableCollection<MediaItem> allItems;
+        private int additionalItemCount = 1;
+
+        public MainViewModel()
+        {
+            PopulateData();
+        }
+
+        public void PopulateData()
+        {
+            var cd = new MediaItem
+            {
+                Id = 1,
+                Name = "Classical Favorites",
+                MediaType = ItemType.Music,
+                MediumInfo = new Medium { Id = 1, MediaType = ItemType.Music, Name = "CD" }
+            };
+
+            var book = new MediaItem
+            {
+                Id = 2,
+                Name = "Classic Fairy Tales",
+                MediaType = ItemType.Book,
+                MediumInfo = new Medium { Id = 2, MediaType = ItemType.Book, Name = "Book" }
+            };
+
+            var bluRay = new MediaItem
+            {
+                Id = 3,
+                Name = "The Mummy",
+                MediaType = ItemType.Video,
+                MediumInfo = new Medium { Id = 3, MediaType = ItemType.Video, Name = "Blu Ray" }
+            };
+
+            Items = new ObservableCollection<MediaItem>
+            {
+                cd,
+                book,
+                bluRay
+            };
+
+            allItems = new ObservableCollection<MediaItem>(Items);
+
+            Mediums = new List<string>
+            {
+                "All",
+                nameof(ItemType.Book),
+                nameof(ItemType.Music),
+                nameof(ItemType.Video)
+            };
+
+            SelectedMedium = Mediums[0];
+        }
+
+        partial void OnSelectedMediumChanged(string value)
+        {
+            Items.Clear();
+
+            foreach (var item in allItems)
+            {
+                if (string.IsNullOrWhiteSpace(value) ||
+                    value == "All" ||
+                    value == item.MediaType.ToString())
+                {
+                    Items.Add(item);
+                }
+            }
+        }
+
+        [RelayCommand]
+        public void AddEdit()
+        {
+            // Note this is temporary until
+            // we use a real data source for items.
+            const int startingItemCount = 3;
+
+            var newItem = new MediaItem
+            {
+                Id = startingItemCount + additionalItemCount,
+                Location = LocationType.InCollection,
+                MediaType = ItemType.Music,
+                MediumInfo = new Medium { Id = 1, MediaType = ItemType.Music, Name = "CD" },
+                Name = $"CD {additionalItemCount}"
+            };
+
+            allItems.Add(newItem);
+            Items.Add(newItem);
+            additionalItemCount++;
+        }
+
+        [RelayCommand(CanExecute = nameof(CanDeleteItem))]
+        public void Delete()
+        {
+            allItems.Remove(SelectedMediaItem);
+            Items.Remove(SelectedMediaItem);
+        }
+
+        private bool CanDeleteItem() => SelectedMediaItem != null;
+    }
+}

Chapter04/Start/MyMediaCollection/ViewModels/MainViewModel.txt

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+using MyMediaCollection.Enums;
+using MyMediaCollection.Model;
+using System.Collections.Generic;
+
+namespace MyMediaCollection.ViewModels
+{
+    public class MainViewModel : BindableBase
+    {
+        private string selectedMedium;
+        private ObservableCollection<MediaItem> items;
+        private ObservableCollection<MediaItem> allItems;
+        private IList<string> mediums;
+        private MediaItem selectedMediaItem;
+        private int additionalItemCount = 1;
+
+        public MainViewModel()
+        {
+            PopulateData();
+        }
+
+        public void PopulateData()
+        {
+            var cd = new MediaItem
+            {
+                Id = 1,
+                Name = "Classical Favorites",
+                MediaType = ItemType.Music,
+                MediumInfo = new Medium { Id = 1, MediaType = ItemType.Music, Name = "CD" }
+            };
+
+            var book = new MediaItem
+            {
+                Id = 2,
+                Name = "Classic Fairy Tales",
+                MediaType = ItemType.Book,
+                MediumInfo = new Medium { Id = 2, MediaType = ItemType.Book, Name = "Book" }
+            };
+
+            var bluRay = new MediaItem
+            {
+                Id = 3,
+                Name = "The Mummy",
+                MediaType = ItemType.Video,
+                MediumInfo = new Medium { Id = 3, MediaType = ItemType.Video, Name = "Blu Ray" }
+            };
+
+            items = new ObservableCollection<MediaItem>
+            {
+                cd,
+                book,
+                bluRay
+            };
+
+            allItems = new ObservableCollection<MediaItem>(Items);
+
+            mediums = new List<string>
+            {
+                "All",
+                nameof(ItemType.Book),
+                nameof(ItemType.Music),
+                nameof(ItemType.Video)
+            };
+
+            selectedMedium = Mediums[0];
+        }
+
+        public ObservableCollection<MediaItem> Items
+        {
+            get
+            {
+                return items;
+            }
+            set
+            {
+                SetProperty(ref items, value);
+            }
+        }
+
+        public IList<string> Mediums
+        {
+            get
+            {
+                return mediums;
+            }
+            set
+            {
+                SetProperty(ref mediums, value);
+            }
+        }
+
+        public string SelectedMedium
+        {
+            get 
+            {
+                return selectedMedium;
+            }
+            set
+            {
+                SetProperty(ref selectedMedium, value);
+
+                Items.Clear();
+
+                foreach (var item in allItems)
+                {
+                    if (string.IsNullOrWhiteSpace(selectedMedium) ||
+                        selectedMedium == "All" ||
+                        selectedMedium == item.MediaType.ToString())
+                    {
+                        Items.Add(item);
+                    }
+                }
+            }
+        }
+
+        public MediaItem SelectedMediaItem
+        {
+            get => selectedMediaItem;
+            set
+            {
+                SetProperty(ref selectedMediaItem, value);
+            }
+        }
+
+        public void AddOrEditItem()
+        {
+            // Note this is temporary until
+            // we use a real data source for items.
+            const int startingItemCount = 3;
+
+            var newItem = new MediaItem
+            {
+                Id = startingItemCount + additionalItemCount,
+                Location = LocationType.InCollection,
+                MediaType = ItemType.Music,
+                MediumInfo = new Medium { Id = 1, MediaType = ItemType.Music, Name = "CD" },
+                Name = $"CD {additionalItemCount}"
+            };
+
+            Items.Add(newItem);
+            additionalItemCount++;
+        }
+
+        public void DeleteItem()
+        {
+            Items.Remove(SelectedMediaItem);
+        }
+    }
+}

Chapter04/Start/MyMediaCollection/ViewModels/MainViewModel2.txt

@@ -0,0 +1,165 @@
+using MyMediaCollection.Enums;
+using MyMediaCollection.Model;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Windows.Input;
+
+namespace MyMediaCollection.ViewModels
+{
+    public class MainViewModel : BindableBase
+    {
+        private string selectedMedium;
+        private ObservableCollection<MediaItem> items;
+        private ObservableCollection<MediaItem> allItems;
+        private IList<string> mediums;
+        private MediaItem selectedMediaItem;
+        private int additionalItemCount = 1;
+
+        public MainViewModel()
+        {
+            PopulateData();
+
+            DeleteCommand = new RelayCommand(DeleteItem, CanDeleteItem);
+
+            // No CanExecute param is needed for this command
+            // because you can always add or edit items.
+            AddEditCommand = new RelayCommand(AddOrEditItem);
+        }
+
+        public void PopulateData()
+        {
+            var cd = new MediaItem
+            {
+                Id = 1,
+                Name = "Classical Favorites",
+                MediaType = ItemType.Music,
+                MediumInfo = new Medium { Id = 1, MediaType = ItemType.Music, Name = "CD" }
+            };
+
+            var book = new MediaItem
+            {
+                Id = 2,
+                Name = "Classic Fairy Tales",
+                MediaType = ItemType.Book,
+                MediumInfo = new Medium { Id = 2, MediaType = ItemType.Book, Name = "Book" }
+            };
+
+            var bluRay = new MediaItem
+            {
+                Id = 3,
+                Name = "The Mummy",
+                MediaType = ItemType.Video,
+                MediumInfo = new Medium { Id = 3, MediaType = ItemType.Video, Name = "Blu Ray" }
+            };
+
+            items = new ObservableCollection<MediaItem>
+            {
+                cd,
+                book,
+                bluRay
+            };
+
+            allItems = new ObservableCollection<MediaItem>(Items);
+
+            mediums = new List<string>
+            {
+                "All",
+                nameof(ItemType.Book),
+                nameof(ItemType.Music),
+                nameof(ItemType.Video)
+            };
+
+            selectedMedium = Mediums[0];
+        }
+
+        public ObservableCollection<MediaItem> Items
+        {
+            get
+            {
+                return items;
+            }
+            set
+            {
+                SetProperty(ref items, value);
+            }
+        }
+
+        public IList<string> Mediums
+        {
+            get
+            {
+                return mediums;
+            }
+            set
+            {
+                SetProperty(ref mediums, value);
+            }
+        }
+
+        public string SelectedMedium
+        {
+            get
+            {
+                return selectedMedium;
+            }
+            set
+            {
+                SetProperty(ref selectedMedium, value);
+
+                Items.Clear();
+
+                foreach (var item in allItems)
+                {
+                    if (string.IsNullOrWhiteSpace(selectedMedium) ||
+                        selectedMedium == "All" ||
+                        selectedMedium == item.MediaType.ToString())
+                    {
+                        Items.Add(item);
+                    }
+                }
+            }
+        }
+
+        public MediaItem SelectedMediaItem
+        {
+            get => selectedMediaItem;
+            set
+            {
+                SetProperty(ref selectedMediaItem, value);
+                ((RelayCommand)DeleteCommand).RaiseCanExecuteChanged();
+            }
+        }
+
+        public ICommand AddEditCommand { get; set; }
+
+        public void AddOrEditItem()
+        {
+            // Note this is temporary until
+            // we use a real data source for items.
+            const int startingItemCount = 3;
+
+            var newItem = new MediaItem
+            {
+                Id = startingItemCount + additionalItemCount,
+                Location = LocationType.InCollection,
+                MediaType = ItemType.Music,
+                MediumInfo = new Medium { Id = 1, MediaType = ItemType.Music, Name = "CD" },
+                Name = $"CD {additionalItemCount}"
+            };
+
+            allItems.Add(newItem);
+            Items.Add(newItem);
+            additionalItemCount++;
+        }
+
+        public ICommand DeleteCommand { get; set; }
+
+        public void DeleteItem()
+        {
+            allItems.Remove(SelectedMediaItem);
+            Items.Remove(SelectedMediaItem);
+        }
+
+        private bool CanDeleteItem() => selectedMediaItem != null;
+    }
+}

Chapter04/Start/MyMediaCollection/ViewModels/RelayCommand.cs

@@ -0,0 +1,33 @@
+using System;
+using System.Windows.Input;
+
+namespace MyMediaCollection.ViewModels
+{
+    public class RelayCommand : ICommand
+    {
+        private readonly Action action;
+        private readonly Func<bool> canExecute;
+
+        public RelayCommand(Action action)
+            : this(action, null)
+        {
+        }
+
+        public RelayCommand(Action action, Func<bool> canExecute)
+        {
+            if (action == null)
+                throw new ArgumentNullException(nameof(action));
+
+            this.action = action;
+            this.canExecute = canExecute;
+        }
+
+        public bool CanExecute(object parameter) => canExecute == null || canExecute();
+
+        public void Execute(object parameter) => action();
+
+        public event EventHandler CanExecuteChanged;
+
+        public void RaiseCanExecuteChanged() => CanExecuteChanged?.Invoke(this, EventArgs.Empty);
+    }
+}

Chapter04/Start/MyMediaCollection/app.manifest

@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="utf-8"?>
+<assembly manifestVersion="1.0" xmlns="urn:schemas-microsoft-com:asm.v1">
+  <assemblyIdentity version="1.0.0.0" name="MyMediaCollection.app"/>
+
+  <compatibility xmlns="urn:schemas-microsoft-com:compatibility.v1">
+    <application>
+      <!--The ID below informs the system that this application is compatible with OS features first introduced in Windows 8. 
+      For more info see https://docs.microsoft.com/windows/win32/sysinfo/targeting-your-application-at-windows-8-1 
+      
+      It is also necessary to support features in unpackaged applications, for example the custom titlebar implementation.-->
+      <supportedOS Id="{4a2f28e3-53b9-4441-ba9c-d69d4a4a6e38}" />
+    </application>
+  </compatibility>
+  
+  <application xmlns="urn:schemas-microsoft-com:asm.v3">
+    <windowsSettings>
+      <!-- The combination of below two tags have the following effect:
+           1) Per-Monitor for >= Windows 10 Anniversary Update
+           2) System < Windows 10 Anniversary Update
+      -->
+      <dpiAware xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">true/PM</dpiAware>
+      <dpiAwareness xmlns="http://schemas.microsoft.com/SMI/2016/WindowsSettings">PerMonitorV2, PerMonitor</dpiAwareness>
+    </windowsSettings>
+  </application>
+</assembly>