[RESOLVED] Best way to load treeview from database.

What is the best to load a treeview from a database where it goes 4 deep

Code:

---

Parent
    child
    child
        grandchild
        grandchild
    child
    child
        grandchild
            great grandhcild
        grandchild

---

How would that look in a database? and then how would you load the tree. I can load everything up to the grandchild, but as soon as I load the great grandchild I start having issues. So I am thinking it is the way they are in the database.

Anybody have any examples they can share?

It depends on the data. It might be stored in four different tables with each record having a foreign key from the table above or it might all be stored in one table with each record containing the ID of its parent. In the second case, loading the data might look like this:

vb.net Code:

Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
    Dim table As New DataTable
 
    'Populate table here.
 
    AddNodes(Me.TreeView1.Nodes, table, Nothing)
End Sub
 
Private Sub AddNodes(nodes As TreeNodeCollection, table As DataTable, parentID As Integer?)
    Dim filter = If(parentID.HasValue, "ParentID = " & parentID, "ParentID IS NULL")
    Dim rows = table.Select(filter)
 
    For Each row In rows
        Dim id = row.Field(Of Integer)("ID")
        Dim node = nodes.Add(id.ToString(), row.Field(Of String)("Name"))
 
        'Make a recursive call to add child nodes to this node.
        AddNodes(node.Nodes, table, id)
    Next
End Sub

The latter is what I have. But it doesn't work when I have grand children. I mean it works but I get repeats of ones that don't belong there. I just wanted to make sure I was doing it correctly.

Either you code is wrong or your data is wrong. We haven't seen either so we can't really help.

its not the most elegant way after seeing your sample code.

http://www.vbforums.com/showthread.php?t=662713

I think I got it. I converted your code to work with mine and it solved the problem. I don't have any bleed over. I knew it was the way I was loading the tree and seeing your code I seen my problem. More efficient too, lol

Thank you JM, much appreciated to lead me in the right direction.