Drag 'n' Drop - How to update data object?

[Rob]

Hello,

I'm working with drag and drop inside a RadTreeView control...  My data objects are pretty simple:

class TreeNode
{
    int ID,
    string Header,
    ObservableCollection<TreeNode> Children,
    TreeNode Parent,    
}

Drag and Drop seems to work well out of the box and updates my children collection appropriately as i move items around...  my question is... what is the best way to update the "Parent" property of a TreeNode after I have moved it.  Is there a way to build my dataobject so this is done automatically?  or do i have to manually do it in one of the drag completed events?

[Petar Mladenov]

Hello Rob,

Suppose we have a RadTreeView consisting of Teams and Players hierarchy. If you move a player from one team to another, you can update your parent or parentId like so:

public Team()
       {
           this.Players = new ObservableCollection<Player>();
           this.Players.CollectionChanged += new System.Collections.Specialized.NotifyCollectionChangedEventHandler(Players_CollectionChanged);
       }
       void Players_CollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
       {
           if (e.Action == System.Collections.Specialized.NotifyCollectionChangedAction.Add)
           {
               Player movedPlayer = (sender as ObservableCollection<Player>)[0] as Player;
               movedPlayer.parentTeam = this;
           }
       }

The CollectionChanged event of the Players collection will fire with every drag and drop operation that moves a player from one team to another.
Please let us know if this approach satisfies you.

All the best,
Petar Mladenov
the Telerik team