Pulling ServerSide Variables Into ClientSide Code

kwilliams · February 5th, 2008, 11:42 AM

I'm trying to pull a server-side variable (VB) into client-side code (JavaScript). I can do this successfully using a regular ASP.NET page, but when I try to implement the same thing using the MasterPage method, I receive an error. I've included the working and non-working code below, along with the results of each. If anyone can please let me know what I'm doing wrong, that would be greatly appreciated. Thanks.

SAMPLE #1: WORKING CODE (SINGLE ASP.NET PAGE)

Code:

<%@ Page Language="VB" Explicit="True" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<script runat="server">
    'Like MasterPage.master.vb
    Dim CurrentState As String = "Colorado"
</script>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<title>Current State</title>
<script language="JavaScript">
<!--
    //Like MasterPage.js
    var currentState = "<% Response.Write(CurrentState) %>";
// -->
</script>
</head>
<script language="JavaScript">
    //Like MasterPage.master
    document.write(currentState);
</script>
</body>
</html>

SAMPLE #1 RESULT: (works properly)
Colorado

SAMPLE #2 NON-WORKING ASP.NET MASTERPAGE:
MasterPage.master.vb

Code:

Partial Class MasterPage
    Inherits System.Web.UI.MasterPage
    Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
        Dim CurrentState As String = "Colorado"
    End Sub
End Class

MasterPage.master

Code:

<%@ Master Language="VB" CodeFile="MasterPageAlerts.master.vb" Inherits="MasterPageAlerts" %>

<!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>Untitled Page</title>
    <script language="JavaScript">
        <!--
        //Like MasterPage.js
        var currentState = "<% Response.Write(CurrentState) %>";
        // -->
    </script>
</head>
<body>
    <form id="form1" runat="server">
    <div>
    <script language="JavaScript">
    //Like MasterPage.master
    document.write(currentState);
</script>
        <asp:contentplaceholder id="ContentPlaceHolder1" runat="server">
        </asp:contentplaceholder>
    </div>
    </form>
</body>
</html>

SAMPLE #2 RESULT: (error)
Compiler Error Message: BC30451: Name 'CurrentState' is not declared.
Line 9: 
Line 13: </script>

KWilliams

dparsons · February 5th, 2008, 02:39 PM

Change this:
Partial Class MasterPage
    Inherits System.Web.UI.MasterPage
    Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
        Dim CurrentState As String = "Colorado"
    End Sub
End Class

to

Partial Class MasterPage
    Inherits System.Web.UI.MasterPage
    Public CurrentState as String
    Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
        CurrentState = "Colorado"
    End Sub
End Class

and this
var currentState = "<% Response.Write(CurrentState) %>";

to
var currentState = "<%= CurrentState %>";

hth

================================================== =========
Read this if you want to know how to get a correct reply for your question:
http://www.catb.org/~esr/faqs/smart-questions.html
================================================== =========
.: Wrox Technical Editor / Author :.
Wrox Books 24 x 7
================================================== =========

dparsons · February 5th, 2008, 02:41 PM

I probably should explain why you need to do that! >< When you declare your variable CurrentState inside of your method like that, it is in scope only to that method and to nothing else. By declaring it as a Public member of the class it is aviable to all methods in your class and thus allows you to use the value on your page.

hth.

================================================== =========
Read this if you want to know how to get a correct reply for your question:
http://www.catb.org/~esr/faqs/smart-questions.html
================================================== =========
.: Wrox Technical Editor / Author :.
Wrox Books 24 x 7
================================================== =========

kwilliams · February 6th, 2008, 04:57 PM

dparsons,

It worked like a charm. Thanks for the solution to what I thought would be a never-ending problem, and thanks for helping me to understand why and how it works in the first place. I REALLY appreciate that. Thanks.:)

KWilliams