Question

am trying to pupulate a treeview nodes base on directory structure like this

Dim arrLinks() As String = Split(Url, "/")

For i As Integer = 0 To arrLinks.Length
    If tvwDirs.Nodes.ContainsKey(arrLinks(0)) = False Then
        tvwDirs.Nodes.Add(arrLinks(0), arrLinks(0))
    End If
Next

The above code works for add base/parent node

say i have a urllike this example.com/dir1/dir2/file

in this case, it should create a child node dir2 in parent node dir1

am getting confused add child nodes to the existing nodes

Answer 1

The first issue you are going to run into is an exception based on your for statement; you should either change it to:

For i As Integer = 0 To arrLinks.Length - 1

or, my preference:

For each nodeKey as String in arrLinks

The next issue is that the Nodes collection does not contain all of the Nodes in the entire tree, it only contains the top level nodes. Each node in this list has its own set of child nodes and each of those children has child nodes, etc.

This means that as you add each node, you need to keep track of the last parent node and add the next child to that parent node or keep track of the current collection of nodes for the level that you are adding to.

This will result in code similar to the following (you may need to adjust the class names for NodeCollection and Node and possible the Add statement (don’t remember off the top if add returns a Node or not)):

Dim arrLinks() As String = Split(Url, "/")
Dim cNodes as NodeCollection

' Keep track of the current collection of nodes, starting with the tree's top level collection
cNodes = tvwDirs.Nodes

For each nodeKey As String in arrLinks
    Dim currentNode as Node

    If Not cNodes.ContainsKey(nodeKey) Then
        ' If the key is not in the current collection of nodes, add it and record the resultant record
        currentNode = cNodes.Add(nodeKey, nodeKey)
    Else
        ' Otherwise, record the current node
        currentNode = cNodes(nodeKey)
    End If
    ' Store the set of nodes that the next nodeKey will be added to
    cNodes = currentNode.Nodes
Next