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Dynamically add nodes to treeview from query pulling data from MS Access

Posted on 2006-06-30
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Last Modified: 2010-05-18
I am using vb 2003 and MS Access 2000.

I need to, when a button is clicked, run a query to pull data from an Access table and populate a treeview with those values.

I already have the dataset working (I can go into preview data). The returned data is system hostnames and is called "hostname".

I would like the treeview to look like

-Server1
-Server2
-Server3
.....

I hope to reuse this type of thing if I could figure out how to add a node to a treeview as a result of a query.

Help!
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Question by:edrz01
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4 Comments
 
LVL 70

Expert Comment

by:Éric Moreau
ID: 17019636
Hi edrz01,

See an article I wrote in April 2006 at http://emoreau.s2i.com/

Cheers!
0
 

Author Comment

by:edrz01
ID: 17019776
Eric,

Thanks for the response. I looked at your code and tried to incorporate it into mine but I am getting an error.

This is my code snippet:

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        Dim ds As New DataSet
        Me.OdbcDataAdapter1.Fill(ds, "HostName")

        With tvServers
            .BeginUpdate()
            .Nodes.Clear()
            For Each drCat As DataRow In DsServerList1.Tables("hostname").Rows        <<<<<<< Error here
                Dim nodParent As TreeNode
                nodParent = tvServers.Nodes.Add(drCat.Item("hostName").ToString)
            Next drCat
            .ExpandAll()
            .EndUpdate()
            .Nodes(0).EnsureVisible()
        End With
    End Sub
----------------------------

The error I am getting in on the line indicated above by the <<<<<

An unhandled exception of type 'System.NullReferenceException' occurred

Any thoughts?
0
 
LVL 70

Accepted Solution

by:
Éric Moreau earned 125 total points
ID: 17019831
isn't your dataset called ds ?

Change this line:
For Each drCat As DataRow In DsServerList1.Tables("hostname").Rows        

for that one:
For Each drCat As DataRow In ds.Tables("hostname").Rows        
0
 

Author Comment

by:edrz01
ID: 17019858
Well, so it is. My oversight! You are a genius. Thank you, thank you, thank you - it worked!

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