Unable to delete child nodes of a parent node (Devexpress TreeList)

Question

I am trying to delete focused node along with it's all child nodes (if any) from TreeList. The problem is I am unable to retrieve the child nodes. I tried 2 approaches:

1. I used TreeListNodeIterator which returns a TreeListNodes object containing childs of the focused row:

   Public Class TreeListOperationGetChildNodes
           Inherits TreeListOperation
           Private _child_nodes As TreeListNodes
   
       Public Sub New(tree As TreeList)
           _child_nodes = New TreeListNodes(tree)
       End Sub
   
       Public Overrides Sub Execute(node As DevExpress.XtraTreeList.Nodes.TreeListNode)
           _child_nodes.Add(node)
       End Sub
   
       Public ReadOnly Property ChildNodes() As TreeListNodes
           Get
               Return _child_nodes
           End Get
       End Property
   
   End Class
   

This child_nodes object is then used to delete all nodes from TreeList:

Dim child_nodes As TreeListNodes = New TreeListNodes(DataTreeList)
Dim op As New TreeListOperationGetChildNodes(DataTreeList)
Dim nodes As TreeListNodes = New TreeListNodes(DataTreeList)
DataTreeList.NodesIterator.DoLocalOperation(op, nodes)
child_nodes = op.ChildNodes 

For Each node As TreeListNode In child_nodes
   DataTreeList.DeleteNode(node)
Next

2. Another Approach I tried was to Loop through all the nodes of the treelist and see if their parent_id is equals to focused node id. If yes then put them into a stack. At the end, for each node in stack call delete node.

   Dim nodeStack As New Stack(Of DevExpress.XtraTreeList.Nodes.TreeListNode)
   nodeStack.Push(DataTreeList.FocusedNode)
   FillStack(DataTreeList.FocusedNode, nodeStack)
   For i As Integer = 0 To nodeStack.Count - 1 Step +1
       DataTreeList.DeleteNode(nodeStack.Pop)
   Next
   
   Private Sub FillStack(ByVal node As DevExpress.XtraTreeList.Nodes.TreeListNode, ByVal nodestack As Stack(Of DevExpress.XtraTreeList.Nodes.TreeListNode))
       For Each childnode As DevExpress.XtraTreeList.Nodes.TreeListNode In DataTreeList.Nodes
   
           If DirectCast(DataTreeList.GetDataRecordByNode(childnode), Data).ParentID = _
              DirectCast(DataTreeList.GetDataRecordByNode(node), Data).ID Then
   
               nodestack.Push(childnode)
               FillStack(childnode, nodestack)
   
           End If
       Next
   End Sub
   

The issue with above code snippets:

1. Here the node iterator is returning chlid_nodes empty (no child nodes found)
2. In FillDeleteStack DataTreeList.Nodes contains only 2 nodes that is only parent nodes. So stack is always empty.

I can not understand why I am not able to iterate through child nodes. Why the collection of nodes in TreeList contains only parent nodes and not child nodes?

Answer 1

0. To delete focused node along with it's all child nodes you can simply use TreeList.DeleteNode method:

DataTreeList.DeleteNode(DataTreeList.FocusedNode)

1. You are using TreeListNodes(TreeList) constructor which creates an empty nodes collection. If you want to get the collection of existing nodes than you can use TreeList.Nodes or TreeListNode.Nodes properties:

nodes = DataTreeList.Nodes
' or
nodes = DataTreeList.FocusedNode.Nodes

2. TreeList.Nodes property returns the collection of the TreeList's root nodes. If you want to get all visible nodes in TreeList then you can use TreeList.GetNodeList method.