Upgrade from ListBox to CollectionViewSource not working - silverlight

Question

I already have a working ListBox with Items from my local database. Now I wanted to upgrade this to a CollectionViewSource for filtering. After my upgrade the new ListBox with CollectionViewSource shows nothing.
MainPage Code Behind:
// Data context for the local database
private BuildingDataContext toDoDB;
// Define an observable collection property that controls can bind to.
private ObservableCollection<Building> _buildings;
public ObservableCollection<Building> BuildingTable
{
get
{
return _buildings;
}
set
{
if (_buildings != value)
{
_buildings = value;
NotifyPropertyChanged("BuildingTable");
}
}
}
public CollectionViewSource Source { get; set; }
// Konstruktor
public MainPage()
{
InitializeComponent();
// Connect to the database and instantiate data context.
toDoDB = new BuildingDataContext(BuildingDataContext.DBConnectionString);
// Data context and observable collection are children of the main page.
this.DataContext = this;
}
protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e)
{
// Define the query to gather all of the to-do items.
var toDoItemsInDB = from Building todo in toDoDB.BuildingTable
select todo;
// Execute the query and place the results into a collection.
BuildingTable = new ObservableCollection<Building>(toDoItemsInDB);
Source = new CollectionViewSource();
Source.Source = BuildingTable;
// Call the base method.base.OnNavigatedTo(e);
}
For that purpose I added the lines:
public CollectionViewSource Source { get; set; }
Source = new CollectionViewSource();
Source.Source = BuildingTable;
I tried as well to put
Source = new CollectionViewSource();
Source.Source = BuildingTable;
in my MainPage Constructor. It doesnt work as well.
My Mainpage.xaml:
<!--<ListBox x:Name="toDoItemsListBox" ItemsSource="{Binding BuildingTable}" Grid.Row="0" Margin="12, 0, 12, 0" Width="440" SelectionChanged="goToNavigation">-->
<ListBox x:Name="toDoItemsListBox" ItemsSource="{Binding Source.View}" Grid.Row="0" Margin="12, 0, 12, 0" Width="440" SelectionChanged="goToNavigation">
<ListBox.ItemTemplate>
<DataTemplate>
<Grid HorizontalAlignment="Stretch" Width="440">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="100" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<TextBlock Name="textBlockShortcut" Text="{Binding Shortcut}" Width="Auto" HorizontalAlignment="Left" Grid.Column="0" Margin="0,0,0,5" FontSize="36" />
<TextBlock Name="textBlockName" Text="{Binding BuildingName}" Width="Auto" HorizontalAlignment="Left" Grid.Column="1" Margin="0,0,0,5" FontSize="36" />
</Grid>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
The first commented line shows the old working listbox without CollectionViewSource. So what am I missing?
EDIT:
private void goToNavigation(object sender, RoutedEventArgs e)
{
// If selected index is -1 (no selection) do nothing
if (toDoItemsListBox.SelectedIndex == -1)
return;
// Navigate to the new page
PhoneApplicationService.Current.State["SelectedItem"] = toDoItemsListBox.SelectedItem;
NavigationService.Navigate(new Uri("/NavigationPage.xaml", UriKind.Relative));
// Reset selected index to -1 (no selection)
toDoItemsListBox.SelectedIndex = -1;
}

Answer 1

You would usually create and bind to a CollectionViewSource in XAML:
<UserControl.Resources>
<CollectionViewSource x:Key="cvs"/>
</UserControl.Resources>
<Grid>
<ListBox ItemsSource="{Binding Source={StaticResource cvs}}" ...>
...
</ListBox>
</Grid>
and in code-behind just access that CollectionViewSource like this:
protected override void OnNavigatedTo(NavigationEventArgs e)
{
...
var cvs = Resources["cvs"] as CollectionViewSource;
cvs.Source = BuildingTable;
}

Answer 2

You don't use the CollectionViewSource class directly, you use a CollectionView of the appropriate type.
View = CollectionViewSource.GetDefaultView( myCollection );
and then you bind that directly to your source.
ItemsSource="{Binding View}"
You can and only should use a CollectionViewSource from xaml, because thats its main purpose. From code you should directly create a CollectionView or use the GetDefaultView method.