WPF

<Window.Resources>
.
.
.
<Style TargetType="{x:Type TreeViewItem}">
        <Setter Property="IsExpanded" Value="{Binding IsExpanded, Mode=TwoWay}" />
    </Style>
.
.
.

<Window.Resources>

<controls:TreeViewEx ItemsSource="{Binding TreeData}"
                             SelectedItemEx="{Binding SelectedTreeItem, Mode=TwoWay}"
                             Grid.Row="0"
                             Grid.Column="0"
                             ItemTemplate="{StaticResource treeDataTemplate}"
                              Style="{DynamicResource TreeViewStyle}">

<HierarchicalDataTemplate x:Key="treeDataTemplate" DataType="{x:Type models:NodeModel}"
                              ItemsSource="{Binding Path=Children}">

Happy Coding

CommandParameter="{Binding}"

private void ExecuteMyCommand(object sender, ExecutedRoutedEventArgs e)
{
  MyModelClass modelItem = (MyModelClass)(e.Parameter);
  // Do whatever you want with the model
}

<controls:TreeViewEx ItemsSource="{Binding TreeItems}"
                        SelectedItemEx="{Binding SelectedTreeLink}"/>

public class TreeViewEx : TreeView
{
    public static readonly DependencyProperty SelectedItemExProperty = DependencyProperty.Register("SelectedItemEx", typeof(object),
         typeof(TreeViewEx), new FrameworkPropertyMetadata(null, new PropertyChangedCallback(OnSelectedItemExChanged)));

    public TreeViewEx()
        : base()
    {
        SelectedItemChanged += new RoutedPropertyChangedEventHandler<object>(TreeViewEx_SelectedItemChanged);
    }

    public object SelectedItemEx
    {
        get { return (object)GetValue(SelectedItemExProperty); }
        set { SetValue(SelectedItemExProperty, value); }
    }

    public bool SelectItem(object item)
    {
        if ((SelectedItem != null) && (SelectedItem.Equals(item)))
            return true;

        if (!ExpandAndSelectItem(this, item))
        {
            UpdateLayout();
            return ExpandAndSelectItem(this, item);
        }

        return true;
    }

    private static void OnSelectedItemExChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        TreeViewEx treeView = d as TreeViewEx;

        if ((object)treeView != null)
            treeView.SelectItem(e.NewValue);
    }

    private void TreeViewEx_SelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
    {
        SetValue(SelectedItemExProperty, e.NewValue);
    }

    private bool ExpandAndSelectItem(ItemsControl parentContainer, object itemToSelect)
    {
        TreeViewItem tvi = parentContainer.ItemContainerGenerator.ContainerFromItem(itemToSelect) as TreeViewItem;

        if ((object)tvi != null)
        {
            tvi.IsSelected = true;
            tvi.BringIntoView();
            tvi.Focus();
            return true;
        }

        for (int nIndex = 0; nIndex < parentContainer.Items.Count; nIndex++)
        {
            TreeViewItem currentContainer = parentContainer.ItemContainerGenerator.ContainerFromIndex(nIndex) as TreeViewItem;

            if (((object)currentContainer != null) && (currentContainer.Items.Count > 0))
            {
                bool bIsExpanded = currentContainer.IsExpanded;

                if (currentContainer.ItemContainerGenerator.Status != GeneratorStatus.ContainersGenerated)
                {
                    EventHandler handler = null;

                    handler = new EventHandler(delegate
                    {
                        if (currentContainer.ItemContainerGenerator.Status == GeneratorStatus.ContainersGenerated)
                        {
                            if (ExpandAndSelectItem(currentContainer, itemToSelect) == false)
                                currentContainer.IsExpanded = false;

                            currentContainer.ItemContainerGenerator.StatusChanged -= handler;
                        }
                    });

                    currentContainer.ItemContainerGenerator.StatusChanged += handler;

                    if (currentContainer.IsExpanded == false)
                        currentContainer.IsExpanded = true;
                }
                else
                {
                    if (ExpandAndSelectItem(currentContainer, itemToSelect) == false)
                        currentContainer.IsExpanded = bIsExpanded;
                    else
                        return true;
                }
            }
        }

        return false;
    }
}