Cannot get Silverlight HierarchicalDataTemplate to display IsolatedStorage folders

Question

This is my first foray into Hierarchical data and am having a bit of a problem.

In Silverlight 4, I am trying to get a list of isolated storage folders to display in a TreeView. Nothing displays at all. My Treeview is completely blank. What am I missing? I am getting data and it is correct.

Any help would be appreciated.

XAML

 <sdk:TreeView x:Name="FolderTreeView" Grid.Column="0" Margin="0,0,3,0" ItemsSource="{Binding _Folders}">
            <sdk:TreeView.ItemTemplate>
                <sdk:HierarchicalDataTemplate ItemsSource="{Binding Path=Folders}">
                    <TextBlock Margin="0" Text="{Binding Name, Mode=OneWay}"/>
                </sdk:HierarchicalDataTemplate>
            </sdk:TreeView.ItemTemplate>
        </sdk:TreeView>

CS

internal class Folder
{
    public Folder() { Folders = new List<Folder>(); }
    public string Name { get; set; }
    public List<Folder> Folders { get; set; }
}

private List<Folder>  _Folders = new List<Folder>();
public OpenFileDialog()
{
    InitializeComponent();

    ifs = IsolatedStorageFile.GetUserStoreForApplication();
    var folder = new Folder
    {
        Name = "Root",
        Folders = (from c in ifs.GetDirectoryNames()
            select new Folder
            {
                Name = c,
                Folders = LoadFolders(c)
            }).ToList()
    };
    _Folders.Add(folder);
    FolderTreeView.DataContext = new { _Folders };
}

private List<Folder>LoadFolders(string folderName)
{
    if(folderName == null)
        return null;
    return (from c in ifs.GetDirectoryNames(folderName + "\\*.*")
        select new Folder
        {
            Name = c,
            Folders = LoadFolders(c)
        }).ToList();
}

Thanks

Answer 1

A few things

<sdk:TreeView x:Name="FolderTreeView" Grid.Column="0" Margin="0,0,3,0" 
              ItemsSource="{Binding _Folders}">

you can't bind to private members.

You need to use ObservableCollections instead of Lists. The binding manager effectively listens for the CollectionChanged events fired by ObservableCollection and notifies the bound controls.

You'll want to implement INotifyPropertyChanged and raise PropertyChanged notifications in your property setters.

Finally, have you set the DataContext for the Treeview?

Also, look in your Output debug window for errors relating to binding.

Edit, ok try:

FolderTreeView.DataContext =  this;

and wrap _Folders in a property

public ObservableCollection <Folder> Folders
    {
    get
       {
       return _Folders;
       }
    set
       {
       _Folders = value;
       OnPropertyChanged("Folders");
       }
   }

change your binding to

<sdk:TreeView x:Name="FolderTreeView" Grid.Column="0" Margin="0,0,3,0" 
              ItemsSource="{Binding Folders}">

I've changed things quite a bit,

    public class Folder : INotifyPropertyChanged
        {

        public Folder(string folderName) 
            {
            Name = folderName;
            Folders = new ObservableCollection<Folder>();
            var _ifs = IsolatedStorageFile.GetUserStoreForApplication();

            if (folderName != null)
                {
                Folders = new ObservableCollection<Folder>(
                        (from c in _ifs.GetDirectoryNames(folderName + "\\*.*")
                         select new Folder(folderName + "\\" + c)
                   ));
                }
            else
                {
                Folders = new ObservableCollection<Folder>(
                       (from c in _ifs.GetDirectoryNames()
                        select new Folder(folderName + "\\" + c)
                  ));
                }
            }


        public string Name { get; set; }

        private ObservableCollection<Folder> _Folders; 
        public ObservableCollection<Folder> Folders 
            {
            get { return _Folders; }
            set { _Folders = value; OnPropertyChanged("RootFolder"); }
            }

        #region INotifyPropertyChanged Members

        public event PropertyChangedEventHandler PropertyChanged;
        protected void OnPropertyChanged(string propertyName)
            {
            if (PropertyChanged != null)
                {
                PropertyChanged(this,
                    new PropertyChangedEventArgs(propertyName));
                }
            }
        #endregion
    }



public partial class OpenFileDialog : UserControl
    {      
    public OpenFileDialog()
        {
        InitializeComponent();

        RootFolder = new Folder (null);
        RootFolders = new ObservableCollection<Folder>();
        RootFolders.Add(RootFolder);

        FolderTreeView.DataContext = this;
        }


    private Folder _RootFolder;
    public Folder RootFolder
        {
        get { return _RootFolder; }
        set { _RootFolder = value; }
        }


    private ObservableCollection<Folder> _RootFolders;
    public ObservableCollection<Folder> RootFolders
        {
        get { return _RootFolders; }
        set { _RootFolders = value; }
        }

    }

xaml

 <sdk:TreeView x:Name="FolderTreeView"  Margin="0,0,3,0" ItemsSource="{Binding RootFolders}">
    <sdk:TreeView.ItemTemplate>
        <sdk:HierarchicalDataTemplate ItemsSource="{Binding Path=Folders}">
            <StackPanel>
            <TextBlock Margin="0" Text="{Binding Name, Mode=OneWay}"/>
            </StackPanel>
        </sdk:HierarchicalDataTemplate>
    </sdk:TreeView.ItemTemplate>
</sdk:TreeView>

Answer 2

Ok...problem solved. Don't understand why though.

I had the ChildWindow set as internal scope instead of public scope because I didn't want the window itself to be viewed external of my Silverlight class library. If anyone can answer why this would stop Hierarchical data binding but not standard data binding I would like to know.