Hi,

I would like to cache a relatively complex treeview with checkboxes to reuse at will a modified configuration (or there is any other method to achive this in a simple way?). The treeview is generated from a database that for practical reasons should not be modified.
When I am trying to restore the control from the cache, it doesn't show in the page. According to the debugger, after generating the tree, the cache and the control seems identical.
I am using the following code (without DB stuff...):

Protected WithEvents tvFilters As Microsoft.Web.UI.WebControls.TreeView
....
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
If Not IsPostBack Then
....
If Cache("treeview") Is Nothing Then
GenerateTreeView()
Else
tvFilters = Cache("treeview")
End If
....
End Sub


Private Sub GenerateTreeView()

....
Dim ds As DataSet = SqlHelper.ExecuteDataset(ConfigurationSettings.AppSettings("connAtum"), CommandType.StoredProcedure, "up_IRT_get_filters_4user", New SqlParameter("@userID", userID))
ds.Relations.Add("NodeRelation", ds.Tables(0).Columns("QAID"), ds.Tables(0).Columns("parentID"))

Dim dbRow As DataRow
For Each dbRow In ds.Tables(0).Rows
If dbRow.IsNull("parentID") Then
Dim node As New TreeNode
node.Text = dbRow("label").ToString
node.Expanded = True
node.ID = dbRow("QAID")
node.DefaultStyle = DefaultCss_0

tvFilters.Nodes.Add(node)
RecursivelyPopulate(dbRow, node)
End If
Next dbRow

End Sub

Private Sub RecursivelyPopulate(ByVal dbRow As DataRow, ByVal node As TreeNode)

Dim childRow As DataRow
For Each childRow In dbRow.GetChildRows("NodeRelation")
Dim childNode As New TreeNode
node.Text = dbRow("label").ToString
node.Expanded = False
node.ID = dbRow("QAID")
childNode.CheckBox = True
childNode.Checked = True
childNode.ID = childRow("QAID")
childNode.Text = childRow("label").ToString
childNode.DefaultStyle = DefaultCss_1
node.Nodes.Add(childNode)
RecursivelyPopulate(childRow, childNode)
Next childRow
End Sub 'RecursivelyPopulate


I would like to cache the treeview configuration submitted by the user:

Public Sub multiselect(ByVal sender As System.Object, ByVal e As System.EventArgs)

....

Dim i, j, k, n As Integer
Dim Val As Integer
Dim Label As String
n = 0
Dim item As ListItem

arParms(7) = New SqlParameter("@fLabel", SqlDbType.NVarChar, 50)

For i = 0 To tvFilters.Nodes.Count - 1
For j = 0 To tvFilters.Nodes(i).Nodes.Count - 1
If tvFilters.Nodes(i).Nodes.Item(j).Checked Then
Val = tvFilters.Nodes(i).Nodes.Item(j).ID
Label = tvFilters.Nodes(i).Nodes.Item(j).Text
....
' filter Input Parameter
End If
For k = 0 To tvFilters.Nodes(i).Nodes.Item(j).Nodes.Count - 1
If tvFilters.Nodes(i).Nodes.Item(j).Nodes.Item(k).Checked Then
Val = tvFilters.Nodes(i).Nodes.Item(j).Nodes.Item(k).ID
Label = tvFilters.Nodes(i).Nodes.Item(j).Nodes.Item(k).Text
....
End If
Next

Next
Next

Cache("treeview") = tvFilters

End Sub



Am I missing anything?

Regards,
Zarko

I found the same issue. I want to cache the treeview object and restore it later, but it doesn't render to the screen. I found there was a private variable _bCreated that is set to false the first time the treeview is being created and then set to _bCreated set to true once it has been created. I believe this variable is used to see if it needs to be rendered to the screen. I'm going to spend more time on this and let you know what I figure out.

Thanks,
Jeff

Hi jbit and zarko,

I have exactly the same problem, and I wondered if you guys found the workaround, so treeview renders on the page when you restore treeview object from cache? I tried to store xml into cache, but binding xml to treeview takes too long, so I thought that storing the entire treeview will be faster to restore from cache. BTW, I have 300 nodes in the treeview. Anybody from Microsoft monitors these forums?

Thanks,

Goran