Loading Data into Treeview Control?

**Larry Lard** · Nov 21 '05, 11:59 AM

Re: Loading Data into Treeview Control?

This is what your code is doing at the moment:

- For each row in the data set
- - create 26 root nodes, one for each letter
- - put this row under the appropriate letter node

Which is why you are getting (I assume) repeating root nodes. What I
recommend you do is this:

- have 'currentLetter' and 'currentNode' variables, initially set to ""
and Nothing
- for each row in the data set
- - if this is a new letter (that is, if left(name,1) <> currentletter)
then:
- - - set currentLetter to left(name, 1)
- - - create a new root node with this letter as its text
- - end if
- - put this row in a new node under currentNode
- next

Note that this method will note create 'empty' root letter notes, ie if
there are no names beginning with X, there will be no X node, etc

How's that work for you?

--
Larry Lard
Replies to group please

**Ken Tucker [MVP]** · Nov 21 '05, 12:00 PM

Re: Loading Data into Treeview Control?

Hi,

Maybe this will help.

Private Sub Form1_Load(ByVa l sender As System.Object, ByVal e As
System.EventArg s) Handles MyBase.Load

Dim conn As SqlConnection

Dim daCustomers As SqlDataAdapter

Dim daOrders As SqlDataAdapter

Dim strConn As String

strConn = "Data Source = " + SystemInformati on.ComputerName

strConn += "\VSdotNet; Initial Catalog = NorthWind;"

strConn += "Integrated Security = SSPI;"

conn = New SqlConnection(s trConn)

daCustomers = New SqlDataAdapter( "Select * from Employees order by LastName,
FirstName", conn)

daCustomers.Fil l(ds, "Clients")

dvCustomers = New DataView(ds.Tab les("Clients"))

AddNodes()

trvNorthWind.So rted = True

End Sub

Private Sub AddNodes()

Dim drCustomer As DataRowView

Dim root As System.Windows. Forms.TreeNode

Dim strName As String

With trvNorthWind

..BeginUpdate()

..Nodes.Clear()

For Each drCustomer In dvCustomers

strName = drCustomer.Item ("FirstName" ) & " " & drCustomer.Item ("LastName")

Dim n As TreeNode

n = New TreeNode(strNam e)

Dim snCountry As TreeNode

Dim snCity As TreeNode

snCity = New TreeNode(drCust omer.Item("City "))

snCountry = New TreeNode(drCust omer.Item("Coun try"))

snCountry.Nodes .Add(snCity)

n.Nodes.Add(snC ountry)

trvNorthWind.No des.Add(n)

Next drCustomer

..EndUpdate()

End With

End Sub

Ken
-------------------------
"Troy" <adamtdavis@hot mail-dot-com.no-spam.invalid> wrote in message
news:4206d85a_4 @127.0.0.1...
I've almost got this the way I want it. I'm loading my customer names
into a treeview control. My problem is I'm repeating my root nodes. I
know it's something to do with my loop structure but My eyes are
crossing from it can someone help me get this organised lol. here's
my code.

Private Sub updateTree()
Dim Conn As Data.OleDb.OleD bConnection = New
Data.OleDb.OleD bConnection
("Provider=Micr osoft.Jet.OLEDB .4.0;Data Source=" & _
OpenFileDialog1 .FileName & ";Persist Security
Info=False;")
Dim DR As Data.OleDb.OleD bDataReader
Dim indx As Short
Dim NoUsers As Boolean
Dim sqlNames As String
Dim currentAlpha As String
Dim sContactName As String

sqlNames = "SELECT ContactID, LastName1, FirstName1,
MiddleInitial1 "
sqlNames = sqlNames & "FROM Contact ORDER BY"
sqlNames = sqlNames & " LastName1, FirstName1,
MiddleInitial1 "
Dim Cmd As Data.OleDb.OleD bCommand = New
Data.OleDb.OleD bCommand
(sqlNames, Conn)

' Clear Treeview Nodes
TreeView1.Nodes .Clear()

Try
Conn.Open()
DR = Cmd.ExecuteRead er

If DR.HasRows = False Then
TreeView1.Nodes .Add("No Users on file")
TreeView1.ForeC olor = Color.Red
NoUsers = True 'Boolean to tell other objects that
there are no users.
Else
TreeView1.ForeC olor = Color.Black
NoUsers = False 'Boolean to tell other objects that
there are users. End If

While DR.Read

For indx = Asc("A") To Asc("Z")
currentAlpha = Chr(indx)
TreeView1.Nodes .Add(New
TreeNode(curren tAlpha))

' Add a child TreeNode for each Customer
object in the current Alpha
Character.
If
UCase(Microsoft .VisualBasic.Le ft(DR("LastName 1"), 1)) = currentAlpha

Then
sContactName = DR("Lastname1" ) & ", "
& DR("FirstName1" ) & " " &
DR("MiddleIniti al1") & "."

System.Windows. Forms.Applicati on.DoEvents()
TreeView1.Nodes (indx - 65).Nodes.Add(N ew
TreeNode(sConta ctName))

End If

Next
End While
DR.Close()
Conn.Close()
End If
Catch LX As Exception
MsgBox(LX.Messa ge, MsgBoxStyle.Exc lamation, "")
End Try
TreeView1.Expan dAll()
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**Troy** · Nov 21 '05, 12:01 PM

re:Loading Data into Treeview Control?

LOL thanks guys I got it to work but here's the kicker.

Works perfect but using Visual Basic .NET 2005 Beta and according to
the tooltip for my fix the command is being taken out after beta is
over and no longer used so back to square one on this.

Here's the code that works though:
Private Sub updateTree()
Dim Conn As Data.OleDb.OleD bConnection = New
Data.OleDb.OleD bConnection("Pr ovider=Microsof t.Jet.OLEDB.4.0 ;Data
Source=" & _
OpenFileDialog1 .FileName & ";Persist Security
Info=False;")
Dim DR As Data.OleDb.OleD bDataReader
Dim indx As Short
Dim NoUsers As Boolean
Dim sqlNames As String
Dim currentAlpha As String
Dim sContactName As String
sqlNames = "SELECT ContactID, LastName1, FirstName1,
MiddleInitial1 "
sqlNames = sqlNames & "FROM Contact ORDER BY"
sqlNames = sqlNames & " LastName1, FirstName1,
MiddleInitial1 "
Dim Cmd As Data.OleDb.OleD bCommand = New
Data.OleDb.OleD bCommand(sqlNam es, Conn)

' Clear Treeview Nodes
TreeView1.Nodes .Clear()

Try

Conn.Open()
DR = Cmd.ExecuteRead er
If DR.HasRows = False Then
TreeView1.Nodes .Add("No Users on file")
TreeView1.ForeC olor = Color.Red
NoUsers = True 'Boolean to tell other objects that
there are no users.
Else
TreeView1.ForeC olor = Color.Black
NoUsers = False 'Boolean to tell other objects that
there are users.

For indx = Asc("A") To Asc("Z")
currentAlpha = Chr(indx)
TreeView1.Nodes .Add(New TreeNode(curren tAlpha))

While DR.Read()
' Add a child TreeNode for each Customer
object in the current Alpha Character.

If
UCase(Microsoft .VisualBasic.Le ft(DR("LastName 1"), 1)) = currentAlpha
Then

sContactName = DR("Lastname1" ) & ", "
& DR("FirstName1" ) & " " & DR("MiddleIniti al1") &
"."

System.Windows. Forms.Applicati on.DoEvents()

TreeView1.Nodes (indx - 65).Nodes.Add(N ew
TreeNode(sConta ctName, 1, 1))

End If
End While
DR.Restart()
Next
DR.Close()
Conn.Close()
End If

Catch LX As Exception
MsgBox(LX.Messa ge, MsgBoxStyle.Exc lamation, "")
End Try
TreeView1.Expan dAll()

The command in [b:1553f9a06b]BOLD[/b:1553f9a06b] is what is being
taken out after Beta is over.

Anyone else know of a way to reset the stack pointer to the top of the
DB again once it had gone through the database once?

or

Offer another approach using the OleDBConnection method?
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Loading Data into Treeview Control?

Loading Data into Treeview Control?

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