The Controls collection cannot be modified because the controlcontains code blocks

[Radu]

Hi. I am trying to localize a page AND simulate the AJAX watermarks in
it, i.e. the textbox contains the text "Enter your name", or "Entrez
votre nom", for instance, then on click, delete this text, allow
entry, but on deletion of the inputted text show again "Enter your
name", or "Entrez votre nom" depending on the UICulture.

Everything worked great UNTIL I have added a button which posts back.
Now on postback I have the error in the title.

This is how it is supposed to work. The page contains the script
<script>
var s=trim('<%= jsTextAddress %>');

function trim(stringToTr im) {
return stringToTrim.re place(/^\s+|\s+$/g,"");
}

function RecipientAddres s_SetToBlank(){
var t=trim(event.sr cElement.value)
if (t == s)
{
event.srcElemen t.value = "";
}
}

function RecipientAddres s_SetToDefault( ){
var t=trim(event.sr cElement.value)
if (t == "")
{
event.srcElemen t.value = s;
}
}
</script>

The "trim" function is necessary because (first stupid unexplained
thing) the clean strings entered in the resource files come back with
lots of Tabs, CRLFs, and spaces (!!!!!!!!?????)

The textarea in question has the HTML
onfocus="Recipi entAddress_SetT oBlank()"
onblur="Recipie ntAddress_SetTo Default()"

The whole thing is supposed to compare the existing string in the
textbox control with the "LOCALIZED" default contents, that is "Enter
your name" or "Entrez votre nom". That's why I need to use the
variable <%= jsTextAddress %instead of comparing it directly with
the "Enter your name" string.

In code behind, in Page Load, I have
jsTextAddress = GetGlobalResour ceObject("Score cards", "String1")

It all worked great - on load the text area showed either "Enter your
name" or "Entrez votre nom", when cliking in the textarea it became
blank waiting for input, if input than the input stays, if the input
is deleted then the contents reverts to either "Enter your name" or
"Entrez votre nom" depending on the culture - exactly as a watermarked
text control is supposed to work.

However, as soon as I have added a postback control on the page, I
have started to receive the error "The Controls collection cannot be
modified because the control contains code blocks" which happens on
System.Web.UI.C ontrolCollectio n.Add(Control child)

How can I fix this please ?
Thanks a lot. Alex.

PS. This is the code for quick pasting in a form named "Welcome.as px":
HTML:

-----------------------------------------------------------------------------------------------------------------------------------------
<%@ Page Language="vb" AutoEventWireup ="false"
CodeBehind="Wel come.aspx.vb" Inherits="Temp2 .Welcome" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://
www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dt d">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
<title>Welcom e</title>
<script>
var s=trim('<%= jsTextAddress %>');

function trim(stringToTr im) {
return stringToTrim.re place(/^\s+|\s+$/g,"");
}

function RecipientAddres s_SetToBlank(){
var t=trim(event.sr cElement.value)
if (t == s)
{
event.srcElemen t.value = "";
}
}

function RecipientAddres s_SetToDefault( ){
var t=trim(event.sr cElement.value)
if (t == "")
{
event.srcElemen t.value = s;
}
}
</script>
</head>

<body>
<form id="frmWelcome " runat="server">
<div>
<textarea
title="<%$ Resources:Score cards, String2 %>"
rows="5"
id="txtRecipien t_Address"
style="width:10 0%;"
onfocus="Recipi entAddress_SetT oBlank()"
onblur="Recipie ntAddress_SetTo Default()"
runat="server">
<%= jsTextAddress %>
</textarea>

<asp:RequiredFi eldValidator
ID="req_txtReci pient_Address1"
Display="Dynami c"
ControlToValida te="txtRecipien t_Address"
Text="*"
InitialValue="< %= jsTextAddress %>"
ErrorMessage="< %$ Resources:Score cards, String5 %>"
runat="server">
</asp:RequiredFie ldValidator>

<asp:RequiredFi eldValidator
ID="req_txtReci pient_Address2"
Display="Dynami c"
ControlToValida te="txtRecipien t_Address"
Text="*"
ErrorMessage="< %$ Resources:Score cards, String5 %>"
runat="server">
</asp:RequiredFie ldValidator>

<asp:Validation Summary
ID="validSummar y"
ShowSummary="fa lse"
DisplayMode="Bu lletList"
HeaderText="<%$ Resources:Score cards, String4 %>"
ShowMessageBox= "true"
runat="server"
/>

<input
type="text"
id="txtRecipien tSummary"
value="<%$ Resources:Score cards, String6%"
runat="server"
title="<%$ Resources:Score cards, String6%"
style="width:10 0%"
/>

<asp:Button
Width="150"
AccessKey="N"
Text="<%$ Resources:Score cards, String7 %>"
ID="cmdOk"
runat="server"
/>
</div>
</form>
</body>
</html>



Code-behind:
-----------------------------------------------------------------------------------------------------------------------------------------
Public Partial Class Welcome
Inherits System.Web.UI.P age

Public jsTextAddress As String

Protected Sub Page_Load(ByVal sender As Object, ByVal e As
System.EventArg s) Handles Me.Load

jsTextAddress = GetGlobalResour ceObject("Score cards", "String1")
End Sub

Protected Overrides Sub InitializeCultu re()

Dim strLang As String

strLang = Context.Request .Params("Langua ge")
If Not String.IsNullOr Empty(strLang) Then
If UCase(strLang) = "FR-CA" Then
UICulture = strLang
Culture = strLang
Session("Langua ge") = "FR-CA"
System.Threadin g.Thread.Curren tThread.Current Culture =
System.Globaliz ation.CultureIn fo.CreateSpecif icCulture(strLa ng)
System.Threadin g.Thread.Curren tThread.Current UICulture = New
System.Globaliz ation.CultureIn fo(strLang)
Else 'Default to language "en"
UICulture = "EN-CA"
Culture = "EN-CA"
Session("Langua ge") = "EN-CA"
System.Threadin g.Thread.Curren tThread.Current Culture =
System.Globaliz ation.CultureIn fo.CreateSpecif icCulture("en-CA")
System.Threadin g.Thread.Curren tThread.Current UICulture = New
System.Globaliz ation.CultureIn fo("en-CA")
End If
End If
End Sub
End Class

[Radu]

Re: The Controls collection cannot be modified because the controlcontains code blocks

I have "solved" the problem... I don't understand why it's solved, the
only thing I did was to take out the inital population of the textbox
"txtRecipient_A ddress" from the HTML and add it to the code-behind,
like so:


HTML:
--------------------------------------------------------------------------------------------------------------
<%@ Page Language="vb" AutoEventWireup ="false"
CodeBehind="Wel come.aspx.vb" Inherits="Temp2 .Welcome" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://
www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dt d">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
<title>Welcom e</title>
<script>
var s=trim('<%= jsTextAddress %>');

function trim(stringToTr im) {
return stringToTrim.re place(/^\s+|\s+$/g,"");
}

function RecipientAddres s_SetToBlank(){
var t=trim(event.sr cElement.value)
if (t == s)
{
event.srcElemen t.value = "";
}
}

function RecipientAddres s_SetToDefault( ){
var t=trim(event.sr cElement.value)
if (t == "")
{
event.srcElemen t.value = s;
}
}
</script>
</head>


<body>
<form id="frmWelcome " runat="server">
<div>
<textarea
title="<%$ Resources:Score cards, String2 %>"
rows="5"
id="txtRecipien t_Address"
style="width:10 0%;"
onfocus="Recipi entAddress_SetT oBlank()"
onblur="Recipie ntAddress_SetTo Default()"
runat="server">
</textarea>

<asp:RequiredFi eldValidator
ID="req_txtReci pient_Address1"
Display="Dynami c"
ControlToValida te="txtRecipien t_Address"
Text="*"
InitialValue="< %= jsTextAddress %>"
ErrorMessage="< %$ Resources:Score cards, String5 %>"
runat="server">
</asp:RequiredFie ldValidator>

<input
type="text"
id="txtRecipien tSummary"
value="<%$ Resources:Score cards, String6%"
runat="server"
title="<%$ Resources:Score cards, String6%"
style="width:10 0%"
/>

<br />

<asp:Button
Width="150"
AccessKey="N"
Text="<%$ Resources:Score cards, String7 %>"
ID="cmdOk"
runat="server"
/>

<asp:Validation Summary
ID="validSummar y"
ShowSummary="fa lse"
DisplayMode="Bu lletList"
HeaderText="<%$ Resources:Score cards, String4 %>"
ShowMessageBox= "true"
runat="server"
/>
</div>
</form>
</body>
</html>


Code behind:
--------------------------------------------------------------------------------------------------------------
Public Partial Class Welcome
Inherits System.Web.UI.P age

Public jsTextAddress As String

Protected Sub Page_Load(ByVal sender As Object, ByVal e As
System.EventArg s) Handles Me.Load

jsTextAddress = Trim(GetGlobalR esourceObject(" Scorecards",
"String1"))
If Not Page.IsPostBack Then
txtRecipient_Ad dress.Value = jsTextAddress
End If
End Sub

Protected Overrides Sub InitializeCultu re()

Dim strLang As String

strLang = Context.Request .Params("Langua ge")
If Not String.IsNullOr Empty(strLang) Then
If UCase(strLang) = "FR-CA" Then
UICulture = strLang
Culture = strLang
Session("Langua ge") = "FR-CA"
System.Threadin g.Thread.Curren tThread.Current Culture =
System.Globaliz ation.CultureIn fo.CreateSpecif icCulture(strLa ng)
System.Threadin g.Thread.Curren tThread.Current UICulture = New
System.Globaliz ation.CultureIn fo(strLang)
Else 'Default to language "en"
UICulture = "EN-CA"
Culture = "EN-CA"
Session("Langua ge") = "EN-CA"
System.Threadin g.Thread.Curren tThread.Current Culture =
System.Globaliz ation.CultureIn fo.CreateSpecif icCulture("en-CA")
System.Threadin g.Thread.Curren tThread.Current UICulture = New
System.Globaliz ation.CultureIn fo("en-CA")
End If
End If
End Sub

Private Sub cmdOk_Click(ByV al sender As Object, ByVal e As
System.EventArg s) Handles cmdOk.Click

Dim objStringBuilde r As StringBuilder = New StringBuilder
Dim strMsg As String

objStringBuilde r.Append("<scri pt language='javas cript'>")

strMsg = "The values of the controls on this page are:"
strMsg = strMsg & "\n" & txtRecipient_Ad dress.Value
strMsg = strMsg & "\n" & txtRecipientSum mary.Value
objStringBuilde r.Append("alert ( """ + strMsg + """ );")

objStringBuilde r.Append("</script>")
ClientScript.Re gisterClientScr iptBlock(Me.Get Type, "Alert",
objStringBuilde r.ToString)
End Sub
End Class
--------------------------------------------------------------------------------------------------------------

Thanks for reading.
Alex.