Can I add buttons with events to a custom treeNode? - asp.net

Question

I extended treeview, treenode, and nodetype so I could have custom nodes. Certain nodes have image buttons on them allowing them to add a child node or delete the node. I can't handle any of the events from my buttons.
Public Class ContentTreeView
Inherits TreeView
Public Event OnAddChild(ByVal sender As Object, ByVal e As EventArgs)
Public Event OnDelete(ByVal sender As Object, ByVal e As EventArgs)
Private _AddImageURL As String = String.Empty
Private _DeleteImageURL As String = String.Empty
Public Property AddImageURL() As String
Get
Return _AddImageURL
End Get
Set(ByVal value As String)
_AddImageURL = value
End Set
End Property
Public Property DeleteImageURL() As String
Get
Return _DeleteImageURL
End Get
Set(ByVal value As String)
_DeleteImageURL = value
End Set
End Property
Protected Overrides Function CreateNode() As TreeNode
Dim retval As ContentTreeNode = New ContentTreeNode(AddImageURL, DeleteImageURL)
AddHandler retval.OnAddChild, AddressOf ContentNode_AddChild
AddHandler retval.OnDelete, AddressOf ContentNode_Delete
Return retval
End Function
Protected Sub ContentNode_AddChild(ByVal sender As Object, ByVal e As EventArgs)
RaiseEvent OnAddChild(Nothing, Nothing)
End Sub
Protected Sub ContentNode_Delete(ByVal sender As Object, ByVal e As EventArgs)
RaiseEvent OnDelete(Nothing, Nothing)
End Sub
Public Class ContentTreeNode
Inherits TreeNode
Public Event OnAddChild(ByVal sender As Object, ByVal e As EventArgs)
Public Event OnDelete(ByVal sender As Object, ByVal e As EventArgs)
Private _AddImageURL As String = String.Empty
Private _DeleteImageURL As String = String.Empty
Private btnAddChild As ImageButton
Private btnDelete As ImageButton
Public Sub New(ByVal AddImageURL_ As String, ByVal DeleteImageURL_ As String)
_AddImageURL = AddImageURL_
_DeleteImageURL = DeleteImageURL_
End Sub
Public Property AddImageURL() As String
Get
Return _AddImageURL
End Get
Set(ByVal value As String)
_AddImageURL = value
End Set
End Property
Public Property DeleteImageURL() As String
Get
Return _DeleteImageURL
End Get
Set(ByVal value As String)
_DeleteImageURL = value
End Set
End Property
Protected Overrides Sub RenderPreText(ByVal writer As HtmlTextWriter)
End Sub
Protected Overrides Sub RenderPostText(ByVal writer As HtmlTextWriter)
CreateChildControls()
If GetTreeNodeType() <> ContentTreeNodeTypes.Root Then
btnAddChild.RenderControl(writer)
If GetTreeNodeType() <> ContentTreeNodeTypes.Category Then
btnDelete.RenderControl(writer)
End If
End If
End Sub
Private Function GetTreeNodeType() As TreeNodeTypes
Dim leaf As TreeNodeTypes = TreeNodeTypes.Leaf
If ((Me.Depth = 0) AndAlso (Me.ChildNodes.Count > 0)) Then
Return ContentTreeNodeTypes.Root
End If
If Me.Depth = 1 Then
Return ContentTreeNodeTypes.Category
End If
If ((Me.ChildNodes.Count <= 0) AndAlso Not Me.PopulateOnDemand) Then
Return leaf
End If
Return ContentTreeNodeTypes.Parent
End Function
Protected Sub CreateChildControls()
'Controls.Clear()
'***Creat Add Button***
btnAddChild = New ImageButton()
btnAddChild.ID = "btnAddChild"
btnAddChild.ImageUrl = AddImageURL
btnAddChild.ToolTip = "Add Child"
AddHandler btnAddChild.Click, AddressOf btnAddChild_Click
'***Create DeleteButton***
btnDelete = New ImageButton()
btnDelete.ID = "btnDelete"
btnDelete.ImageUrl = DeleteImageURL()
btnDelete.ToolTip = "Delete Page"
AddHandler btnDelete.Click, AddressOf btnDelete_Click
''***Add Controls***
'Me.Controls.Add(btnAddChild)
'Me.Controls.Add(btnDelete)
End Sub
Protected Sub btnAddChild_Click(ByVal sender As Object, ByVal e As EventArgs)
RaiseEvent OnAddChild(Nothing, Nothing)
End Sub
Protected Sub btnDelete_Click(ByVal sender As Object, ByVal e As EventArgs)
RaiseEvent OnDelete(Nothing, Nothing)
End Sub
Public Enum ContentTreeNodeTypes
All = 7
Leaf = 4
None = 0
Parent = 2
Root = 1
Category = 3
End Enum
End Class
End Class
1) Can I implement something like IPostBackEventHandler?
2) Is this possible since treeNode isn't a control/webcontrol?
Any help is appreciated... Thanks!!!

Answer 1

I think the problem is timing related, meaning the child controls are added to late in the ASP.Net page lifecycle for the event to be executed.
This might solve the issue:
Compose the whole tree structure as early as possible, e.g. in the Init event of the page.
Append the child ImageButton in the constructor of the ContentTreeNode.
Alternatively you could use a javascript context-menu so you wouldn't need to append any child-controls to the TreeNode...

Answer 2

After reading this post. I decided to use the following solution. First I changed my CreateChildControls method to:
Protected Sub CreateChildControls()
Dim page As Page = HttpContext.Current.CurrentHandler
Dim csm As ClientScriptManager = page.ClientScript
Dim control As WebControl = page.Master.FindControl(_ContainerID).FindControl(_ContentTreeViewID)
'***Creat Add Button***
btnAddChild = New ImageButton()
btnAddChild.ID = "btnAddChild"
btnAddChild.ImageUrl = AddImageURL
btnAddChild.ToolTip = "Add Child"
btnAddChild.Attributes.Add("onClick", csm.GetPostBackEventReference(control, String.Format("{0}:{1}", Me.Value, "Add")))
'***Create DeleteButton***
btnDelete = New ImageButton()
btnDelete.ID = "btnDelete"
btnDelete.ImageUrl = DeleteImageURL()
btnDelete.ToolTip = "Delete Page"
btnDelete.Attributes.Add("onClick", csm.GetPostBackEventReference(control, String.Format("{0}:{1}", Me.Value, "Delete")))
End Sub
Then I had to implement IPostBackEventHandler in the custom treeview to handle the postback events. Maybe not the best solution but it works well with custom event args.