This is a really weird one - I will do my best to explain.
I have a basic master page:
<%@ Master Language="VB" CodeFile="MasterPage.master.vb" Inherits="master_MasterPage" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
<asp:ContentPlaceHolder ID="head" runat="server">
</asp:ContentPlaceHolder>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:ContentPlaceHolder ID="ContentPlaceHolder1" runat="server">
</asp:ContentPlaceHolder>
<asp:PlaceHolder ID="PH1" runat="server" />
<asp:PlaceHolder ID="PH2" runat="server" />
</div>
</form>
</body>
</html>
And a standard child page:
<%@ Page Title="" Language="VB" MasterPageFile="~/master/MasterPage.master" AutoEventWireup="false" CodeFile="Default.aspx.vb" Inherits="master_Default" %>
<asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
</asp:Content>
I have the following extension methods for finding controls recursively:
Option Strict On
Option Explicit On
Imports System.Runtime.CompilerServices
Imports System.Web.UI
Public Module ExtensionMethods
<Extension()> _
Public Function FindControlRecursively(ByVal parentControl As System.Web.UI.Control, ByVal controlID As String) As System.Web.UI.Control
If parentControl.ID = controlID Then
Return parentControl
End If
For Each c As System.Web.UI.Control In parentControl.Controls
Dim child As System.Web.UI.Control = FindControlRecursively(c, controlID)
If child IsNot Nothing Then
Return child
End If
Next
Return Nothing
End Function
<Extension()> _
Public Function FindControlIterative(ByVal rootControl As Control, ByVal controlId As String) As Control
Dim rc As Control = rootControl
Dim ll As LinkedList(Of Control) = New LinkedList(Of Control)
Do While (rc IsNot Nothing)
If rc.ID = controlId Then
Return rc
End If
For Each child As Control In rc.Controls
If child.ID = controlId Then
Return child
End If
If child.HasControls() Then
ll.AddLast(child)
End If
Next
rc = ll.First.Value
ll.Remove(rc)
Loop
Return Nothing
End Function
End Module
I have a control with a listview:
<%@ Control Language="VB" AutoEventWireup="false" CodeFile="control-1.ascx.vb" Inherits="controls_control_1" %>
<p>
Control 1</p>
<asp:ListView ID="lv" runat="server">
<ItemTemplate>
<div>
<asp:Literal ID="Name" runat="server" Text='<%#Eval("Name") %>' />
<asp:LinkButton ID="TestButton" runat="server">Test</asp:LinkButton>
</div>
</ItemTemplate>
</asp:ListView>
That is databound:
Partial Class controls_control_1
Inherits System.Web.UI.UserControl
Protected Sub Page_Load(sender As Object, e As System.EventArgs) Handles Me.Load
If Not Page.IsPostBack Then
Dim l As New List(Of Person)
Dim j As New Person
j.Name = "John"
l.Add(j)
lv.DataSource = l
lv.DataBind()
End If
End Sub
End Class
Public Class Person
Public Property Name As String
End Class
I have a second control that is very basic:
<%@ Control Language="VB" AutoEventWireup="false" CodeFile="control-2.ascx.vb" Inherits="controls_control_2" %>
<p>Control 2</p>
In my child page, I have the following code to load the controls:
Option Strict On
Option Explicit On
Partial Class master_Default
Inherits System.Web.UI.Page
Protected Sub Page_Init(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Init
Dim controlInstance1 As System.Web.UI.Control = LoadControl("~/controls/control-1.ascx")
controlInstance1.ID = "control_1"
Dim zone As System.Web.UI.Control = Me.Master.FindControlRecursively("PH1")
zone.Controls.Add(controlInstance1)
Dim controlInstance2 As System.Web.UI.Control = LoadControl("~/controls/control-2.ascx")
controlInstance2.ID = "control_2"
Dim zone2 As System.Web.UI.Control = Me.Master.FindControlRecursively("PH2")
zone2.Controls.Add(controlInstance2)
End Sub
End Class
This loads the controls, but if I click the Test button in the listview, the page loses the data in the listview after postback.
If I change the FindControlRecursively calls to FindControlIterative, when I click the test button, the data in the listview is retained after the postback.
Anybody have any idea what the FindControlRecursively call might be doing to cause the listview to lose it's data? This only happens if control-2 is added to the page - if it is not, and control-1 is loaded using FindControlRecursively, data is retained correctly after postback.
Thanks in advance...this one is driving me nuts, and it took me a while to figure out where exactly it was breaking down.
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