CODEWITHSUNDEEP
vb.nettreeview
mazrabul
mazrabul

Reputation: 295

Loop through treeview nodes to delete certain nodes

Hello and thanks in advance for your help.

I have a treeview that is populated from a HDD folder collection. Its structure is similar to the following (however the structure is dynamic):

My Disk:
|
|--folder1(tag:folder)
|  |--subfolder1(tag:folder)
|--folder2(tag:folder)
|--folder3(tag:folder)
|--folder4(tag:folder)
   |file1(tag:file)

I would like to delete all nodes from the tree that do not contain nodes with the tag "file" (basically empty folders). I would like the resulting tree structure to look like this:

My Disk:
|--folder4(tag:folder)
   |file1(tag:file)

The best that I have come up with is the following:

Private Sub deleteNode(byval nc as TreeNodeCollection)
 For Each tn As TreeNode In nc
  'delete node if it applies
        If tn.Tag = "folder" Then
            If tn.Nodes.Count = 0 Then
                 nc.Remove(tn)
            End If
        End If

        If tn.Nodes.Count > 0 Then
             deleteNode(tn.Nodes)
        End If
    Next
End Sub

I call the sub as follows:

deleteNode(treeview1.Nodes(0).Nodes)

However, the above is not working properly. It deletes only some nodes and not all the targeted nodes. Could you please help me out by fixing my sub?

Many thanks

Upvotes: 2

Views: 11373

Answers (2)

Bobby
Bobby

Reputation: 11576

As far as I know, you can't edit the collection you're enumerating, so that it removes some nodes is also impressive.

You might wanna try another approach:

Private Sub RemoveEmptyFolderNodes(ByVal nc as TreeNodeCollection)
    For i As Integer = nc.Count - 1 To 0 Step -1
        If nc(i).Nodes.Count > 0 Then
            RemoveEmptyFolderNodes(nc(i).Nodes)
        End If
        If nc(i).Nodes.Count = 0 AndAlso nc(i).Tag.ToString() = "folder" Then
            nc.RemoveAt(i)
        End If                
    Next
End Sub

This is untested.

Upvotes: 4

Paulo Bueno
Paulo Bueno

Reputation: 2569

The treeview is initially populated by our program?

If so simply don't add the nodes with that tag.

If not, the for each loop is a problem since the treenode collection is been changed every time you call the remove node function.

I've solved this by creating a collection to store the keys to be removed and AFTER the for each loop you may safely remove the nodes you want. gl.

For example:

Dim nNd As Node
Dim toDel As New Collection

For Each nNd In tvSS.Nodes
    If nNd.tag="whatuwant" Then toDel.Add (nNd.Key)
Next
Do While toDel.Count > 0
    tvSS.Nodes.Remove (toDel.Item(1))
    toDel.Remove (1)
Loop
Set toDel = Nothing

Upvotes: 0

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