treenode tag returning strange value.

[Fuga]

Hi all,

I´ve finally managed to assign an array to a treenode tag, displaying the tag(0) as tooltip.

However, on the nodedoubleclick event, I want to get the tag(0) value to navigate a bindingsource, and the tag always returns 8, no matter which node I click. 8 is the number of treenodes if that has anything to do with it.

this is the code:

    Private Sub TreeView1_NodeMouseDoubleClick(ByVal sender As System.Object, ByVal e As System.Windows.Forms.TreeNodeMouseClickEventArgs) Handles TreeView1.NodeMouseDoubleClick
        Dim pos As Integer
        pos = Me.TreeView1.SelectedNode.Tag(0)
        Evaluate.BindingSource3.Position = pos
        Evaluate.updat()
    End Sub

Thanks!

Fuga.

[jmcilhinney]

The Tag property is type Object and you can't index an Object, so you obviously have Option Strict turned Off for a start. I suggest you remedy that first up. If you have an Integer array stored in the Tag then you should first cast it as that type.

[Fuga]

-edited-

[Fuga]

Thanks for your help.

I turned on option strict, and that gave me an error that it disallowes "late binding".

I did a search on the forum and I found some posts, but I just don´t understand it. What does late binding mean?

I think I need to give the whole code.

In one module, the treeview is populated:

    Sub createtreeview()
        Dim tvds As New DataSet
        Dim tvda As New OleDb.OleDbDataAdapter
        Dim tvrw As DataRow
        Dim kval As Integer
        Dim tvselcom As New OleDb.OleDbCommand
        Dim tv As New TreeView
        Dim tvnode As New System.Windows.Forms.TreeNode
        Dim tagcontent(1) As Integer

        tors.TreeView1.Nodes.Clear()
        tors.TreeView1.Nodes.Add("rootnode1")
        tors.TreeView1.Nodes.Add("rootnode2")
        tors.TreeView1.Nodes.Add("rootnode3")
        tors.TreeView1.Nodes.Add("rootnode4")
        tvselcom.CommandText = "....."
        tvselcom.Connection = torcon
        tvda.SelectCommand = tvselcom
        tvda.Fill(tvds, "tor")
        tv = tors.TreeView1
        kval = 0
        For Each tvrw In tvds.Tables(0).Rows
            tvnode = New TreeNode
            tagcontent.SetValue(kval, 0)
            tagcontent.SetValue(Evaluate.BindingSource3.Position, 1)
            tvnode.Tag = tagcontent
            tvnode.Text = tvrw.Item("....").ToString
            tvnode.ToolTipText = tvnode.Tag(0).ToString
            tors.TreeView1.Nodes(0).Nodes.Add(tvnode)
            If tvnode.Tag(0).ToString = Evaluate.TextBox7.Text Then
                tors.TreeView1.SelectedNode = tvnode
            End If
            kval = kval + 1
        Next
        tvds.Clear()
        tvda.SelectCommand.CommandText = "....."
        tvda.Fill(tvds, "tor")
        For Each tvrw In tvds.Tables(0).Rows
            tvnode = New TreeNode
            tagcontent.SetValue(kval, 0)
            tagcontent.SetValue(Evaluate.BindingSource3.Position, 1)
            tvnode.Tag = tagcontent
            tvnode.Text = tvrw.Item("rubrik").ToString
            tvnode.ToolTipText = tvnode.Tag(0).ToString
            tors.TreeView1.Nodes(1).Nodes.Add(tvnode)
            If tvnode.Tag(0).ToString = Evaluate.TextBox7.Text Then
                tors.TreeView1.SelectedNode = tvnode
            End If
            kval = kval + 1
        Next
        tvds.Clear()
        tvda.SelectCommand.CommandText = "...."
        tvda.Fill(tvds, "tor")
        For Each tvrw In tvds.Tables(0).Rows
            tvnode = New TreeNode
            tagcontent.SetValue(kval, 0)
            tagcontent.SetValue(Evaluate.BindingSource3.Position, 1)
            tvnode.Tag = tagcontent
            tvnode.Text = tvrw.Item("rubrik").ToString
            tvnode.ToolTipText = tvnode.Tag(0).ToString
            Faktors.TreeView1.Nodes(2).Nodes.Add(tvnode)
            If tvnode.Tag(0).ToString = Evaluate.TextBox7.Text Then
                tors.TreeView1.SelectedNode = tvnode
            End If
            kval = kval + 1
        Next
        tvds.Clear()
        tvda.SelectCommand.CommandText = "...."
        tvda.Fill(tvds, "tor")
        For Each tvrw In tvds.Tables(0).Rows
            tvnode = New TreeNode
            tagcontent.SetValue(kval, 0)
            tagcontent.SetValue(Evaluate.BindingSource3.Position, 1)
            tvnode.Tag = tagcontent
            tvnode.Text = tvrw.Item("rubrik").ToString
            tvnode.ToolTipText = tvnode.Tag(0).ToString
            tors.TreeView1.Nodes(3).Nodes.Add(tvnode)
            If tvnode.Tag(0).ToString = Evaluate.TextBox7.Text Then
               tors.TreeView1.SelectedNode = tvnode
            End If
            kval = kval + 1
        Next
        tvds.Clear()
        tors.TreeView1.ExpandAll()
        tors.Refresh()
    End Sub

This makes four rootnodes that are always the same, and then childnodes varying over the rootnodes. This works.

Just to check it, I set the tooltiptext to display the tag(0), which is the thing I want to use for navigation on the bindingsource:

 Private Sub TreeView1_NodeMouseDoubleClick(ByVal sender As System.Object, ByVal e As System.Windows.Forms.TreeNodeMouseClickEventArgs) Handles TreeView1.NodeMouseDoubleClick

        Evaluate.BindingSource3.Position = Me.TreeView1.SelectedNode.Tag(0)
        Evaluate.updat()
    End Sub

Now if the tooltiptext displays 4, how come the me.treeview1.selectednode.tag(0) gives 8?


Greatful for all help!
Fuga.

[Shaggy Hiker]

Option Strict will mean that you will explicitly have to tell the compiler what types you are using. In your first post, JM noted that you were treating an object as if it were an array. You felt this was safe because you KNEW it was an array. However, the compiler doesn't know that. With Option Strict OFF, you are telling the compiler to go ahead and assume that you know what you are talking about (and if you don't, you pay for it). That may seem fine to you, but you pay for that freedom, and the price is not worth it. Setting Option Strict ON means that you will have to explicitly tell the compiler that, "Yes! This IS an array" before it will be willing to use an object as an array. The result of this is that you will write better code, but you will also write faster code. More typing for you, but less effort at runtime, hence faster performance. Insignificant in this case, but still something that needs to be done.

As for the question, I don't have a precise answer, as Treeviews can behave in some unexpected fashions in my experience. However, I would suggest that at the position where the oddity occurs, put a breakpoint on the line, and have a look. I think the line might be this one:

Evaluate.BindingSource3.Position = Me.TreeView1.SelectedNode.Tag(0)

if I read the question right. I would want to look at two things:

1) What is in SelectedNode.Tag?
2) What is SelectedNode?

My first thought, without seeing the code in action, is that SelectedNode might not be what you think it is. Failing that, then the Tag doesn't hold what you expect it to hold.

[Fuga]

Thanks

Yes you´re right about the failing line.

1. the tag holds two values: 8 and 0.
2. VB says the me.treenode1.selectednode.tag(0) is a system.array

It´s all very strange. When I hover the mouse, the value displayed is the right index of the treenode, but when I doubleclick, suddenly it´s index 8.

Actually it is the number of treenodes. When I added a post the index is 9.

Fuga.

[Shaggy Hiker]

The next step I would take would be to set a breakpoint back where you load the Treeview so that you can watch each and every one getting filled. If that shows the right thing being filled, then put the breakpoint on the line in question and step through from there. If the value is right at the time the breakpoint is hit, but it still displays wrong then the options are these:

1) Some code is changing the value, stepping through the code should show that. The most likely possibility, from my semi-informed perspective, would be that the one event is triggering another event that you are not expecting.
2) You are not displaying what you think you are (the tooltip, or whatever is set wrong. Not likely, but it IS one of the options).
3) The node you think you are working with is not the node you are actually working with. I think you may have covered this one.

[FourBlades]

I wouldn't say "Option Strict will mean that you will explicitly have to tell the compiler what types you are using."
To make the point more clear I'd say turning on Option Strict will cause VB to disallow you from making implicit narrowing conversions that might subsequently fail; or worse, yield invalid and yet unknown erroneous results. Then, with Option Strict on, you'll have to cast explicitly as previously noted in post #5.