Unable to fire TreeView properties events - wpf

Question

I am having problem with the following code. I have a TreeView Control which is bound to a Collection. The TreeView does get populated with the desired results. HOwever the "IsSelected" property and ContextMenu's click Command is not firing. Following is the XAML code.
<UserControl x:Class="Plan.Views.PadView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:v="clr-namespace:Planner.Views"
xmlns:vm="clr-namespace:Planner.ViewModels"
<Grid>
<StackPanel Orientation="Vertical">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<StackPanel Grid.Row="1" Grid.Column="0" Orientation="Horizontal" OpacityMask="#FFECF5F5">
<TreeView ItemsSource="{Binding Pads}" Name="tree_View" Width="190">
<TreeView.ItemContainerStyle >
<Style TargetType="{x:Type TreeViewItem}">
<Setter Property="IsSelected" Value="{Binding WellPadViewModel.IsSelected}" />
<Setter Property="ContextMenu">
<Setter.Value>
<ContextMenu>
<MenuItem Header="Rename" Command="{Binding RelativeSource={RelativeSource AncestorType={x:Type TreeView}}, Path=DataContext.RenameCommand}" />
</ContextMenu>
</Setter.Value>
</Setter>
<Style.Triggers>
<Trigger Property="IsSelected" Value="True">
</Trigger>
</Style.Triggers>
</Style>
</TreeView.ItemContainerStyle >
<TreeView.ItemTemplate>
<HierarchicalDataTemplate ItemsSource="{Binding Members}">
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding Name}" >
<TextBlock.InputBindings>
<KeyBinding Key="F2" Command="{Binding RenameCommand}"/>
</TextBlock.InputBindings>
</TextBlock>
</StackPanel>
</HierarchicalDataTemplate>
</TreeView.ItemTemplate>
</TreeView>
</StackPanel>
</Grid>
</StackPanel>
</Grid>
</UserControl>
And here is my ViewModel
using System;
using System.Collections.ObjectModel;
using System.Windows;
using System.Windows.Input;
using System.ComponentModel;
using WPFApplication;
namespace FieldPlanner.ViewModels
{
public class PlanViewModel : BaseViewModel
{
Collection<Pads> pads = new Collection<Pads>();
public PlanViewModel()
{
IsSelected = true;
pads = new Collection<Pad>();
}
private ICommand _RenameCommand;
public ICommand RenameCommand
{
get
{
if (_RenameCommand == null)
{
_RenameCommand = new RelayCommand1((o) =>
{
// Your logic should go here
MessageBox.Show("Please rename me");
});
}
return _RenameCommand;
}
}
public ObservableCollection<PadInfo> Members { get; set; }
private static object _selectedItem = null;
// This is public get-only here but you could implement a public setter which also selects the item.
// Also this should be moved to an instance property on a VM for the whole tree, otherwise there will be conflicts for more than one tree.
public static object SelectedItem
{
get { return _selectedItem; }
private set
{
if (_selectedItem != value)
{
_selectedItem = value;
OnSelectedItemChanged();
}
}
}
public static void OnSelectedItemChanged()
{
// Raise event / do other things
}
private bool _isSelected;
public bool IsSelected
{
get { return _isSelected; }
set
{
if (_isSelected != value)
{
_isSelected = value;
OnPropertyChanged("IsSelected");
if (_isSelected)
{
SelectedItem = this;
}
}
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
var handler = this.PropertyChanged;
if (handler != null)
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
/// <summary>
/// Class to hold the Pads info for a tree
/// </summary>
public class Pad
{
/// <summary>
/// Default Constructor
/// </summary>
public Pad()
{
this.Members = new ObservableCollection<PadInfo>();
}
/// <summary>
/// Name of the pad
/// </summary>
public string Name { get; set; }
/// <summary>
/// Members of the pad
/// </summary>
public ObservableCollection<PadInfo> Members { get; set; }
}
/// <summary>
/// Class to hold the well and slot IDs snapped to a pad
/// </summary>
public class PadInfo
{
/// <summary>
/// Slot ID
/// </summary>
public string SlotID { get; set; }
/// <summary>
/// Well ID
/// </summary>
public string WellID { get; set; }
}
public class RelayCommand1 : ICommand
{
#region Fields
readonly Action<object> _execute;
readonly Predicate<object> _canExecute;
#endregion // Fields
#region Constructors
public RelayCommand1(Action<object> execute)
: this(execute, null)
{
}
public RelayCommand1(Action<object> execute, Predicate<object> canExecute)
{
if (execute == null)
throw new ArgumentNullException("execute");
_execute = execute;
_canExecute = canExecute;
}
#endregion // Constructors
#region ICommand Members
// [DebuggerStepThrough]
public bool CanExecute(object parameter)
{
return _canExecute == null ? true : _canExecute(parameter);
}
public event EventHandler CanExecuteChanged
{
add { CommandManager.RequerySuggested += value; }
remove { CommandManager.RequerySuggested -= value; }
}
public void Execute(object parameter)
{
_execute(parameter);
}
#endregion // ICommand Members
}
}
How can I identify the issue?

Answer 1

You have two problems:
IsSelected:
<Setter Property="IsSelected" Value="{Binding WellPadViewModel.IsSelected}" />
In TreeViewItem DataContext is set to instance of Pad and Pad doesn't have property IsSelected You have to do sth like this:
<Setter Property="IsSelected" Value="{Binding DataContext.IsSelected, RelativeSource={RelativeSource AncestorType={x:Type UserControl}}" />
Problem with ContextMenu is much more sirious. ContextMenu isn't in VisualTree so you cannot bind to RelativeSource. Solution is here WPF Relative source- Cannot find source for binding with reference
Best regards

Answer 2

Please set the Tag property in your DataTemplate to TreeViewItem. I have sth like this:
<DataTemplate>
<Grid Width="270" Height="20" Tag="{Binding DataContext, RelativeSource = {RelativeSource AncestorType={x:Type UserControl}}}">
...
<Grid.ContextMenu>
<ContextMenu DataContext="{Binding PlacementTarget, RelativeSource={RelativeSource Self}}">
<MenuItem Header="Edit">
<i:Interaction.Triggers>
<i:EventTrigger EventName="Click">
<command:EventToCommand Command="{Binding Tag.YOURCOMMAND}"/>
</i:EventTrigger>
</i:Interaction.Triggers>
</MenuItem>
</ContextMenu>
</Grid.ContextMenu>
</Grid>
</DataTemplate>
It should work.