Why doesn't the following WPF treeview work?

Question

It's been a really long time since iv'e used WPF, now, required to do a small project on it, I have a really weird problem making a simple databinded treeview.

the main window so far:

public partial class MainWindow : Window, INotifyPropertyChanged
{
    public MainWindow()
    {
        InitializeComponent();

        populateTreeview();
    }

    private XMLDataNode tree;

 public XMLDataNode TreeRoot
 {
     get { return tree; }
     set 
     { 
          tree = value;
          NotifyPropertyChanged("TreeRoot");
     }
 }

    //Open the XML file, and start to populate the treeview
    private void populateTreeview()
    {
        {
            try
            {
                //Just a good practice -- change the cursor to a 
                //wait cursor while the nodes populate    
                this.Cursor = Cursors.Wait;
                string filePath = System.IO.Path.GetFullPath("TestXML.xml");
                TreeRoot = RXML.IOManager.GetXMLFromFile(filePath).Last();
            }
            catch (XmlException xExc)
            //Exception is thrown is there is an error in the Xml
            {
                MessageBox.Show(xExc.Message);
            }
            catch (Exception ex) //General exception
            {
                MessageBox.Show(ex.Message);
            }
            finally
            {
                this.Cursor = Cursors.AppStarting; //Change the cursor back
            }
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;

    public void NotifyPropertyChanged(string propName)
    {
        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(propName));
    }
}

The data class i'm working with which loads XML nodes into itself:

public class XMLDataNode
{
    public XmlNode node;
    public string Title;
    public List<XMLDataNode> Children;

    public XMLDataNode(XmlNode XMLNode)
    {
        this.node = XMLNode;
        this.Title = node.ToString();
        Children = new List<XMLDataNode>();
        foreach (XmlNode item in XMLNode.ChildNodes)
        {
            Children.Add(new XMLDataNode(item));
        }
    }

the mainwindow XAML:

<Window x:Class="RotemXMLEditor.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="MainWindow" Height="800" Width="1000" x:Name="me">
<Grid>
    <Grid.RowDefinitions>
        <RowDefinition />
        <RowDefinition />
    </Grid.RowDefinitions>

    <TreeView Grid.Row="1" x:Name="treeView" Background="White" ItemsSource="{Binding ElementName=me, Path=TreeRoot}">
        <TreeView.ItemTemplate>
            <HierarchicalDataTemplate ItemsSource="{Binding Children}">
                <TextBlock Text="{Binding Title}"/>
            </HierarchicalDataTemplate>
        </TreeView.ItemTemplate>

    </TreeView>
</Grid>

The current output is an empty treeview, with nothing in it, even though the databinded object is filled with info.

I realize it's probably a silly mistake, but I really can't seem to find the mistake, Help?

Answer 1

Can you turn this property in a collection that implements IEnumerable?

public XMLDataNode TreeRoot

eg:

public XMLDataNode[] TreeRoots

The ItemsSource of the TreeView expects a type that implements IEnumerable

This works for me:

<TreeView Grid.Row="1" x:Name="treeView" Background="White" ItemsSource="{Binding ElementName=me, Path=TreeRoots}">
    <TreeView.ItemTemplate>
        <HierarchicalDataTemplate ItemsSource="{Binding Children}">
            <TextBlock Text="{Binding Title}"/>
        </HierarchicalDataTemplate>
    </TreeView.ItemTemplate>
</TreeView>

private XMLDataNode[] treeRoots;
public XMLDataNode[] TreeRoots
{
    get { return treeRoots; }
    set
    {
        treeRoots = value;
        NotifyPropertyChanged("TreeRoots");
    }
}

private void populateTreeview()
    {
        {
            try
            {
                //Just a good practice -- change the cursor to a 
                //wait cursor while the nodes populate    
                this.Cursor = Cursors.Wait;
                string filePath = System.IO.Path.GetFullPath("TestXML.xml");
                TreeRoot = RXML.IOManager.GetXMLFromFile(filePath).Last();
                TreeRoots = new[] { TreeRoot };
            }
            catch (XmlException xExc)

Answer 2

I have found the solution.

WPF databinding can only work (which I forgot) with properties, not fields, even though the fields are public, changing all the data binded fields to actual properties solves this problem.