Drag, Drop, and IndexOf

[Special Ed]

I am populating a treeview control from a database. I want to allow the user to drag and drop nodes to arrange the nodes in a sort order. I was trying to use the DragEnded event to get the new position in the tree and update the new position in the database. I thought I could use the IndexOf to get the new position in the tree the node is located. If I drag a root node the Items.IndexOf for the dragged node returns the correct position, lower level nodes return -1. The code I am using is as follows:

    Private Sub RadTreeView1_DragEnded(ByVal sender As Object, ByVal e As Telerik.Windows.Controls.RadTreeViewDragEndedEventArgs) Handles RadTreeView1.DragEnded

        Dim newSortOrder As Integer
        Dim parentId As Integer

        Dim draggedItem As RadTreeViewItem = e.DraggedItems(0)
        Dim eStore As eStoreDataDataContext = New eStoreDataDataContext

        If IsNothing(draggedItem.ParentItem) Then
            ' no parent then item is root node
            parentId = 0
        Else
            parentId = draggedItem.ParentItem.Tag.ToString
        End If

        newSortOrder = RadTreeView1.Items.IndexOf(draggedItem)

        MsgBox("parentId = " & parentId.ToString)
        MsgBox("newSortOrder = " & newSortOrder.ToString)

    End Sub

 I am using the tag property to identify the parentId value in my database table. Does anyone know why the Items.IndexOf returns a number corresponding to the order the item is displayed in the tree for root node items and -1 for all other nodes?

Thanks.

[Valentin.Stoychev]

Hello Special Ed,

You can use the TargetDropItem and to get its Index property. This, combined with the DropPosition property of the event args you can calculate the new index of the item.

You will need to get the latest internal build, because there is a fix that sets properly the TargetDropItem.

Please let us know if you need more info on that.

Regards,
Valentin.Stoychev
the Telerik team

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[Special Ed]

When you say calculate are you referring to the index being a 0 base collection. The index I would want in my example would be the index returned plus 1.

 

Ed

[Kiril Stanoev]

Hi Special Ed,

I have attached an example demonstrating how you can retrieve the index property of the dropped item.
Please have a look at it and if you have any questions or comments, let us know.

Kind regards,
Kiril Stanoev
the Telerik team

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