NullReferenceException in RadAjaxManager.AjaxSettings.AddAjaxSetting()

[Nathan J Pledger]

Hi,

I have a Page Controller design pattern, so I have a base Page class that defines and dumps out a RadAjaxManager control. The (edited) base class is:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Web;
using System.Xml;
using xxx.yyy.ASPNET.Security;
using xxx.yyy.Client;
using xxx.yyy.Client.Security;
using xxx.yyy.Core;
using Telerik.Web.UI;

namespace xxx.yyy.ASPNET
{
    public class AuthenticatedyyyPage : yyyPageBase
    {
        private RadAjaxManager _radAjaxManager=null;

        #region ~ Properties ~

        public RadAjaxManager AjaxManager
        {
            get { return _radAjaxManager; }
        }

        #endregion

        protected override void OnLoad(EventArgs e)
        {
            // set up global AJAX Manager
            _radAjaxManager = BuildRadAjaxManager();
            Form.Controls.Add(_radAjaxManager);

            if (!ClientScript.IsClientScriptBlockRegistered(_radAjaxManager.ClientID))
            {
                ClientScript.RegisterClientScriptBlock(_radAjaxManager.GetType(), _radAjaxManager.ClientID,GenerateJavascript(),true);
            }


            base.OnLoad(e);
        }

        protected virtual RadAjaxManager BuildRadAjaxManager()
        {
            RadAjaxManager radAjaxManager = new RadAjaxManager();
            radAjaxManager.ID = "radAjaxManager";
            return radAjaxManager;
        }

        private string GenerateJavascript()
        {
            StringBuilder sb = new StringBuilder();



            sb.Append("\n\nfunction migGetRadAjaxManager() {\n");
            sb.Append("\tvar ajaxManager=$find(\"" + _radAjaxManager.ClientID + "\");\n");
            sb.Append("\treturn ajaxManager;\n");
            sb.Append("}\n\n");


            return sb.ToString();
        }
    }
}

(The RadAjaxManager is added into the Form and appears in the rendered HTML)

In the derived page, I want to add an AjaxSetting programmatically (as per http://www.telerik.com/help/aspnet-ajax/ajxaddajaxsettingsprogrammatically.html) in the Page_Load():

protected void Page_Load(object sender, EventArgs e)
        {
            AjaxManager.AjaxRequest += new RadAjaxControl.AjaxRequestDelegate(AjaxManager_AjaxRequest);

            AjaxManager.AjaxSettings.AddAjaxSetting(btnCancel0, pnlScriptInjector);

        }

But this results in the exception:

Object reference not set to an instance of an object.

AjaxManager.AjaxSettings.AddAjaxSetting(btnCancel0, pnlScriptInjector);

   at Telerik.Web.UI.AjaxSettingsCollection.AddAjaxSetting(Control ajaxifiedControl, Control updatedControl)
   at xxx.yyy.ASPNET.Presentation.Secure.Admin.ImportWindowsUsers.Page_Load(Object sender, EventArgs e) in c:\dev2008\yyy2\yyy_WEB\secure\admin\ImportWindowsUsers.aspx.cs:line 128
   at System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e)
   at System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e)
   at System.Web.UI.Control.OnLoad(EventArgs e)
   at xxx.yyy.ASPNET.yyyBase.OnLoad(EventArgs e) in C:\dev2008\yyy2\xxx.yyy.ASPNET\yyyPageBase.cs:line 45
   at xxx.yyy.ASPNET.Authenticatedyyy.OnLoad(EventArgs e) in C:\dev2008\yyy\xxx.yyy.ASPNET\AuthenticatedyyyPage.cs:line 138
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

Inspecting the variables in the debugger and I can't see anything that is null.

Could you please tell me why is this happening? Am I using it right?

[SamJ]

Hi Nathan,

Have you tried adding the RadAjaxManager to the form controls collection OnInit instead of OnLoad event? I think that when the manager is added later than OnInit it is unable to initialize properly.

Does this helps?

Regards,
SamJ

[Nathan J Pledger]

hi,

Thanks, that works fine, though I have had to put my code in a RadCodeBlock.

The particular case does not work, however.

I have the following scenario:

User clicks a toolbar button (a wrapper control for RadToolbar), behaviour of which is defined by the AjaxSetting:

        protected override void OnPreRender(EventArgs e)
        {
            AjaxManager.AjaxSettings.AddAjaxSetting(btnSelectUsers, pnlScriptInjector);

            base.OnPreRender(e);
        }

Toolbar runs JavaScript that calls the RadAjaxManager.AjaxRequest method:

ajaxManager.ajaxRequest('ImportWindowsUsers_NotifyUsers')

This then runs fine, which sends some emails off, and I then inject some Javascript into the pnlScriptInjector panel:

	private void AjaxManager_AjaxRequest(object sender, AjaxRequestEventArgs e)
	{
	switch (e.Argument)
	{
	case "ImportWindowsUsers_NotifyUsers":
	//                  ....
	StringBuilder sb = new StringBuilder();
	sb.Append("\n\n<script type=\"text/javascript\">\n//<![CDATA[\n\n");
	sb.Append("radalert(\"<strong>" + emailsSent.ToString("#,##0") + "</strong> email successfully sent to users.<br /><br />");
	if (emailsNotSent>0) sb.Append("<strong>"+emailsNotSent.ToString("#,##0")+"</strong> users could not be emailed because they do not have Email Addresses available within their Windows User Account record.<br /><br />");
	if (emailsFailed>0) sb.Append("<strong class=\"red\">"+emailsFailed.ToString("#,##0")+"</strong> users may not have been emailed due to errors in sending the email.<br /><br />");
	sb.Append("As a precaution, consider Exporting the created User records to a <acronym title=\"Comma Separated Value\">CSV</acroynym> or Microsoft Excel file.\",400,200,\"Users Notified\");\n");
	sb.Append("\n\n//]]>\n\n</script>\n\n");
	pnlScriptInjector.Controls.Add(new LiteralControl(sb.ToString()));
	break;
	}
	}

Am I being too adventurous/optimistic to expect the AjaxSetting handle my injecting JavaScript into the pnlScriptInjector for it to run following the server-side operation? No script appears in the pnlScriptInjector element when I inspect the DOM post AJAX.

[SamJ]

Hi Nathan,

I haven't try this approach for script injection. But I assume that you could use the ResponseScript property of the ajax manager for this purpose. So your modified code should be something like this:

private void AjaxManager_AjaxRequest(object sender, AjaxRequestEventArgs e)
{
     switch (e.Argument)
     {
          case "ImportWindowsUsers_NotifyUsers":
            //                  ....
                StringBuilder sb = new StringBuilder();
                sb.Append("radalert(\"<strong>" + emailsSent.ToString("#,##0") +
                    "</strong> email successfully sent to users.<br /><br />");
               if (emailsNotSent>0) sb.Append("<strong>" + emailsNotSent.ToString("#,##0") +
                  "</strong> users could not be emailed because they do not have Email Addresses available within their Windows User Account record.<br /><br />");
               if (emailsFailed>0) sb.Append("<strong class=\"red\">" + emailsFailed.ToString("#,##0") +
                  "</strong> users may not have been emailed due to errors in sending the email.<br /><br />");
           sb.Append("As a precaution, consider Exporting the created User records to a <acronym title=\"Comma Separated Value\">CSV</acroynym> or Microsoft Excel file.\",400,200,\"Users Notified\");\n");
           ajaxManager.ResponseScripts.Add(sb.ToString());
               break;
    }
}

Does this works for you?

Thanks
SamJ

[Nathan J Pledger]

That definitely works for me.

You should publish more on that, I haven't seen that method before.

[Sphengle]

I too had the same exception using the AddAjaxSetting() method.  Nothing seemed to work for me except this long winded approach....

AjaxSetting

 

setting = new AjaxSetting();

 

 

AjaxUpdatedControl target = new AjaxUpdatedControl (rgdTLA.ID, rlp.ID );

 

setting.UpdatedControls.Add(target);

setting.AjaxControlID = lnk.ID ;

 

radAjaxManager.AjaxSettings.Add(setting);

[Jack]

I had the same issue as well.  This was remedied by ensuring that I had specified a value for the ID property of the ajaxifiedControl parameter (that being the control initiating an update).