Common Function for Checking nodes of treeview?

[rajesh.forum]

Hi all!
i need Common function to check if there is existing nodes in treeview.
i cud nt write a function for this because the user will enter the node dynamically in my form.Please assume that there is 'n' no of node levels..
I ve used "for each" loop for each nodes and its childs..
Here is the sample code that i ve tried..

 For Each tNode As TreeNode In tvMenu.Nodes
                                If tNode.Text = tbMenuName.Text Then
                                    errMenu.ForeColor = Color.Red
                                    errMenu.Text = "Menu Name Already Exist"
                                Else
                                    For Each child As TreeNode In tNode.Nodes
                                        If child.Text = tbMenuName.Text Then
                                            errMenu.ForeColor = Color.Red
                                            errMenu.Text = "Menu Name Already Exist"
                                        End If
                                    Next
                                End If
Next

With regards
rajesh

 

[JohnH]

You can save yourself the trouble and set the Name of treenode equal to the Text when you create it. The Name property you see is used as key for the TreenodeCollection.Find method, and it has search recursive option.

If tvMenu.Nodes.Find(tbMenuName.Text, True) IsNot Nothing Then
    'node found
    'errMenu.ForeColor = Color.Red
    'errMenu.Text = "Menu Name Already Exist"
End If

If you wanted to learn how to write a recursive function like the Find method above then here is also an example of this:

Function NodeExists(ByVal nodes As TreeNodeCollection, ByVal text As String) As Boolean
    For Each node As TreeNode In nodes
        If node.Text = text Then Return True
        If NodeExists(node.Nodes, text) Then Return True '<---- see the function call itself, recursive !!
    Next
    Return False
End Function

called similar to above:

If NodeExists(tvMenu.Nodes, tbMenuName.Text) Then
    'node found
    'errMenu.ForeColor = Color.Red
    'errMenu.Text = "Menu Name Already Exist"
End If

Notice also that is not the job of this function to change your UI elements, its only job is to search and return result. It's OOP good practise. When you get the result you decide what to do with it, this means many people can use this function for different purposes.