spring:head and ajax control toolkit

**EJS** · 05-29-2007, 08:18 PM

Hi all,

My ASP.NET 2.0 webapp uses a Masterpage (Spring.Web.UI.Masterpage). Pages extend Spring.Web.UI.Page. This all works fine. I added Spring Ajax integration as well, this also works fine. However, when using the AjaxControlToolkit, e.g. the MaskedEditExtender, I get the following error:

Code:

[NullReferenceException: Object reference not set to an instance of an object.]
   AjaxControlToolkit.ScriptObjectBuilder.RegisterCssReferences(Control control) +295
   AjaxControlToolkit.ExtenderControlBase.OnPreRender(EventArgs e) +138

When googling to resolve this problem I found this: http://odetocode.com/Blogs/scott/arc.../25/10627.aspx.

It states "that the themes feature in ASP.NET 2.0 relies on an active header control to inject style sheets, I figured the ScriptObjectBuilder used the same trick to inject new script tags".

When using a <head> tag with runat="server" the problem is fixed indeed, but then the

Code:

<%= Page.CssRoot %>

that works because of the spring:head tag doesn't work anymore...

Is this an issue with the spring:head tag? Are there any fixes or workarounds?

Thanks in advance,
EJ

**Erich Eichinger** · 05-31-2007, 02:38 PM

Hi,

could you maybe provide a bit more of your .aspx code?

tx,
Erich

**EJS** · 05-31-2007, 07:54 PM

Hi Erich,

Thanks for your reaction.

This is the MasterPage with original spring:head tag

Code:

<%@ Master Language="C#" AutoEventWireup="true" CodeBehind="Site.Master.cs" Inherits="EJSSD.BrokerTool.Web.SiteMaster" Debug="true"%>

<!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" >
  <spring:Head id="Head1" runat="server">
    <link href="<%= Page.CssRoot %>/default.css" type="text/css" rel="stylesheet" />
    <title><%= GetMessage("default.title") %></title>
    <asp:ContentPlaceHolder id="head" runat="server" />
  </spring:Head>
  <body>
    <form id="form" method="post" runat="server">
      <div id="container">
        <div id="logo">
          <spring:LocalizedImage id="logoImage" imageName="spring-air-logo.jpg" borderWidth="0" runat="server" />
        </div>
        <div id="content">
       ................

which gives the error described above, when used with this content page:

Code:

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="EditApplication.aspx.cs" Inherits="EJSSD.BrokerTool.Web.EditApplication" %>
<asp:content id="editAppContent" contentplaceholderid="body" runat="server">
    <table cellspacing="0" cellpadding="0" width="90%" align="center" border="0">
        <tr>
            <td>
                <asp:label id="lblAppName" runat="server" text="Name"/>
            </td>
            <td>
				<asp:textbox id="txtAppName" runat="server" />
            </td>
        </tr>
        <tr>
            <td>
                <asp:label id="lblStartDate" runat="server" text="Start date"/>
            </td>
            <td>
				<asp:textbox id="txtStartDate" runat="server" />
				<ajaxToolkit:CalendarExtender id="startDateExtender" runat="server" TargetControlID="txtStartDate"
				 Format="dd-MM-yyyy"/>
            </td>
        </tr>
..................

I colored the AjaxControlToolkit tag to better show where it is used.

Problem is not present when changing the Masterpage to:

Code:

.........
<head id="head" runat="server">
	<title>Survey</title>
	<link href="css/default.css" type="text/css" rel="stylesheet" />
</head>
............

Thanks so far,
EJ

**Erich Eichinger** · 05-31-2007, 08:37 PM

Hi,

Please try nesting <spring:Head> within asp.net's <head>:

Code:

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <spring:Head runat="server">
      <link href="<%= Page.CssRoot %>/default.css" type="text/css" rel="stylesheet" />
      <title><%= GetMessage("default.title") %></title>
    </spring:head>
      <asp:ContentPlaceHolder id="head" runat="server" />
  </head>
...

unfortunately it has not been possible to merge the 2 functionalities. Thus if you need both, <spring:head> allows to be nested within standard <head> tag.

-Erich

**EJS** · 05-31-2007, 09:14 PM

Thanks Erich, that works fine..., albeit with two heads...

Cheers,
EJ

**Erich Eichinger** · 05-31-2007, 09:20 PM

Hi,

I know it's not beautiful. But as long as NET framework developers tend to make everything sealed and private, I'm afraid there's little choice :-(

-Erich

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