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CSS Treeview Adapter losing checkbox state

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User753892747 posted

I am using the css treeview adapter. It appears that when I do a postback using a checkbox control and set the items programatically, the items do not stay checked. If I use a button to set the items, it works fine. If anybody has any idea, please let me know.

Here is a simple test:

HTML:

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Untitled Page</title>
    <script language='JavaScript' type='text/javascript' src='/scripts/CascadeCheckmarks.js'></script>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:CheckBox ID="chkCheckItem" runat="server" Text="Check last two items" AutoPostBack="true" />
        <br />
        <asp:Button ID="btnCheckItem" runat="server" Text="Check first two items" />
        <asp:TreeView ID="tvListProspect" OnClientClickedCheckbox="CascadeCheckmarks(event)"
            runat="server" CssSelectorClass="SicTreeView" ShowCheckBoxes="All">
        </asp:TreeView>
    </div>
    </form>
</body>
</html>

vb:

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        If Not IsPostBack Then
            LoadList()
        End If
    End Sub
    Private Sub LoadList()
        Dim node As TreeNode
            node = New TreeNode
            node.Value = "0"
            node.Text = "0"
            node.ShowCheckBox = True
            Me.tvListProspect.Nodes.Add(node)

            node = New TreeNode
            node.Value = "1"
            node.Text = "1"
            node.ShowCheckBox = True
            Me.tvListProspect.Nodes.Add(node)

            node = New TreeNode
            node.Value = "2"
            node.Text = "2"
            node.ShowCheckBox = True
            Me.tvListProspect.Nodes.Add(node)

            node = New TreeNode
            node.Value = "3"
            node.Text = "3"
            node.ShowCheckBox = True
            Me.tvListProspect.Nodes.Add(node)

            node = New TreeNode
            node.Value = "4"
            node.Text = "4"
            node.ShowCheckBox = True
            Me.tvListProspect.Nodes.Add(node)

            node = New TreeNode
            node.Value = "5"
            node.Text = "5"
            node.ShowCheckBox = True
            Me.tvListProspect.Nodes.Add(node)
    End Sub

    Protected Sub btnCheckItem_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnCheckItem.Click
            Me.tvListProspect.Nodes(0).Checked = True
            Me.tvListProspect.Nodes(1).Checked = True
    End Sub

    Protected Sub chkCheckItem_CheckedChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles chkCheckItem.CheckedChanged
            Me.tvListProspect.Nodes(4).Checked = chkCheckItem.Checked
            Me.tvListProspect.Nodes(5).Checked = chkCheckItem.Checked
    End Sub

Monday, March 31, 2008 2:42 PM

Answers

User753892747 posted

After some digging, it appears the problem is in LoadPostData and UpdateCheckmarks. I believe that LoadPostData wasn't ever implemented right at all.

Here is what I found out: It appears that UpdateCheckMarks only checks for objects that are in page.request.form, meaning either you checked them on the screen and hit a submit type, or you loaded the tree dynamically on page load and checked some items. If you were to dynamically check the nodes on a non submit postback, it wouldn't work, which was the original problem. Once I understood the problem, someone on the team I work with suggested to put the ones I want checked (on a non submit postback) in the context object. So I created an arraylist, added the items I wanted checked then modified UpdateCheckMarks like so:

Private Sub UpdateCheckmarks(ByVal items As TreeNodeCollection)
            Dim treeView As TreeView = CType(Control, TreeView)
            If ((Not (treeView) Is Nothing) AndAlso (Not (items) Is Nothing)) Then
                For Each item As TreeNode In items
                    If IsCheckbox(treeView, item) Then
                        Dim name As String = (treeView.UniqueID + ("n" _
                                    + (_checkboxIndex.ToString + "CheckBox")))
                        Dim bIsNowChecked As Boolean = (Not (Page.Request.Form(name)) Is Nothing)

                        If bIsNowChecked Then '<- added this, item is not in page.request.form
                            If (item.Checked <> bIsNowChecked) Then
                                item.Checked = bIsNowChecked
                                Extender.RaiseAdaptedEvent("TreeNodeCheckChanged", New TreeNodeEventArgs(item))
                            End If
                        Else
                            If HttpContext.Current.Items.Contains("NewCheckedNodes") Then '<-check to see if context object contains my new arraylist, if it does, process 
                                Dim newCheckedNodes As ArrayList = HttpContext.Current.Items.Item("NewCheckedNodes")

                                If newCheckedNodes.Contains(item) Then
                                    item.Checked = True
                                Else
                                    item.Checked = False
                                End If                                
                            Else
                                item.Checked = False
                            End If
                            
                            item.ImageToolTip = ""
                        End If

                        _checkboxIndex = (_checkboxIndex + 1)
                    End If
                    If HasChildren(item) Then
                        UpdateCheckmarks(item.ChildNodes)
                    End If
                Next
            End If
        End Sub

Marked as answer by Anonymous Thursday, October 7, 2021 12:00 AM

Tuesday, April 1, 2008 10:34 AM

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CSS Treeview Adapter losing checkbox state

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