Question

I hoped the answer to my previous question whould help me with this one, but it didn’t. The initial situation is pretty much the same:

<TreeView ItemsSource='{Binding Groups}' Name='tvGroups' AllowDrop='True'>           <TreeView.ItemTemplate>                     <HierarchicalDataTemplate ItemsSource='{Binding Participants}'>                           <StackPanel Orientation='Horizontal' Drop='tvDrop' Tag='{Binding .}'>                                <TextBlock Text='{Binding Name}' />                                <Button Tag='{Binding .}' Click='Button_Click_2'>                                     <Image Source='Resources/cross.png' />                                 </Button>                           </StackPanel>                           <HierarchicalDataTemplate.ItemTemplate>                               <DataTemplate>                                   <StackPanel Orientation='Horizontal' >                                        <TextBlock Text='{Binding Alias}' />                                        <Button Tag='{Binding .}' Name='btnDeleteParticipants' Click='btnParticipants_Click' >                                             <Image Source='Resources/cross.png' />                                        </Button>                                   </StackPanel>                               </DataTemplate>                           </HierarchicalDataTemplate.ItemTemplate>                     </HierarchicalDataTemplate>           </TreeView.ItemTemplate> </TreeView> 

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 private void btnParticipants_Click(object sender, RoutedEventArgs e)//Probanten aus Gruppe entfernen         {             Participant p = ((sender as Button).Tag as Participant);             if (p == null) return;             //TODO: Raus bekommen in welcher Gruppe ich löschen will          } 

I want to remove Participant p from a Group by clicking the button(btnDeleteParticipants). I tried something like this one:

Control c = sender as Control; while (!(c is TreeViewItem))      c = (c.Parent) as Control; 

But this didn’t work (don’t ask why, I’m not sure). I could find the Group by checking if it contains the Participant(bound to btnDeleteParticipants.Tag), but this would disallow participants to be in more than 1 group. So, any ideas how to get the right Group?

Edit:

Groups = new ObservableCollection<Group>(); Participants = new ObservableCollection<Participant>(); 

Answer 1

Are Groups and Participants ObservableCollection objects?

Try using this:

static TObject FindVisualParent<TObject>(UIElement child) where TObject : UIElement {   if (child == null)   {     return null;   }    UIElement parent = VisualTreeHelper.GetParent(child) as UIElement;    while (parent != null)   {     TObject found = parent as TObject;     if (found != null)     {       return found;     }     else     {       parent = VisualTreeHelper.GetParent(parent) as UIElement;     }   }    return null; } 

Also, try using the DataContext to get the participant and set the Tag to the TemplatedParent.

<Button Tag='{Binding RelativeSource={RelativeSource TemplatedParent}}' /> 

Then on click

private void btnParticipants_Click(object sender, RoutedEventArgs e) {   var button = sender as Button;   var p = button.DataContext as Participant;   if (p == null) return;    var t= FindVisualParent<TreeViewItem>(button); // get the Participants TreeViewItem   if (t == null) return;   var groupTreeItem = FindVisualParent<TreeViewItem>(t);  // get the groups TreeViewItem   if (groupTreeItem == null) return;   var group = groupTreeItem.DataContext as Group;   group.Participants.Remove(p); }