category1
  -  category2
       -  item1
       -  item2
       -  item3
  -  category3
       -  item4
category4
  -  item5
  -  item6
category5
  -  category6

Above is an example of my treeview I'm working with.  I would like to conditionally enable/disable drag and drop functionality per node type. 
If a node is an item:
  -  it can be dragged into (over) a node that is empty or already has other items in it
  -  it can be dragged next to (above/below) a node that is

If a node is a category:
  -  it can be dragged into (over) a node as long as that destination node does not have item child nodes

Is there any way to set this in code when the page loads either through code or attributes?  I have dropping disabled on all item nodes.  I know that I can check the node types on postback, but I'm wanting to not let the user perform the drop initially based on the above criteria, therefore eliminating the unnecessary  postback.  Please help.

Hello,


You could handle this in "OnClientNodeDropping" event of RadTreeView. You cna easily cancel the event using "set_cancel()" method based on your conditions.

A more clear idea, you will get by going through the documentation.
OnClientNodeDropping



Thanks,
Princy.

Does this event fire when dragging a node over another node or only when the user releases the mouse button?  I don't want to cancel the drop, I want to the user to see that they can't drop it there, basically like setting AllowDrop to false, just conditionally.

Maybe as a future idea for the treeview, have a field (perhaps using the Category field) that tells the node it can only accept, for dropping, nodes of a specified type or types.

Hi Preston,

This functionality is not that trivial to achieve. You will need to handle at least 2 events and on each drag and drop to traverse the entire TreeView resetting cssClasses.

My advice is to catch the dropping event and to notify the user post the action.


Regards,
Nikolay Tsenkov
the Telerik team