Gridview does not load items properly with Ajax Manager

[JD Emmert]

Hi, I am trying to use RadAjaxManager to cause my gridview to add items when a button is clicked.  These items are stored in a session variable.  When I use the RadUpdatePanel, everything works as expected, except the whole page reloads and is slow.  I would like to show a loading panel over each contorl that is loading (my actual page is quite complex).  When I click the button to add an item to the radgrid, it shows the loading panel, but the grid does not show any new items.  However if I click other things on the page, the items that were added will appear.  I've been searching for quite some time for a solution to my problem.  Also note:I'm trying NOT to use javascript if possible.  My setup is as follows:

<%@ Page Title="Home Page" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true"
    CodeBehind="Default.aspx.cs" Inherits="WebApplication5._Default" %>

<%@ Register assembly="Telerik.Web.UI" namespace="Telerik.Web.UI" tagprefix="telerik" %>

<asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent">
</asp:Content>
<asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent">

    <telerik:RadScriptManager ID="scmAjax" runat="server" ScriptMode="Release" />

    <telerik:RadAjaxManager ID="radAjaxManager" runat="server">
        <AjaxSettings>
            <telerik:AjaxSetting AjaxControlID="radAjaxManager">
                <UpdatedControls>
                    <telerik:AjaxUpdatedControl ControlID="RadGrid1" LoadingPanelID="rlpLoadingPanel"/>
                </UpdatedControls>
            </telerik:AjaxSetting>
            <telerik:AjaxSetting AjaxControlID="RadButton1">
                <UpdatedControls>
                    <telerik:AjaxUpdatedControl ControlID="RadGrid1" LoadingPanelID="rlpLoadingPanel"/>
                </UpdatedControls>
            </telerik:AjaxSetting>
            <telerik:AjaxSetting AjaxControlID="RadGrid1">
                <UpdatedControls>
                    <telerik:AjaxUpdatedControl ControlID="RadGrid1" LoadingPanelID="rlpLoadingPanel"/>
                </UpdatedControls>
            </telerik:AjaxSetting>
        </AjaxSettings>
    </telerik:RadAjaxManager>


    <telerik:RadButton ID="RadButton1" runat="server" Text="Assign"
        onclick="RadButton1_Click" AutoPostBack="true">
    </telerik:RadButton>

    <telerik:RadButton ID="RadButton2" runat="server" Text="Request that will reload grid"
        AutoPostBack="true">
    </telerik:RadButton>

    <telerik:RadGrid ID="RadGrid1" runat="server" GridLines="None">
    </telerik:RadGrid>

    <telerik:RadAjaxLoadingPanel ID="rlpLoadingPanel" runat="server" Skin="Default" IsSticky="false">
        </telerik:RadAjaxLoadingPanel>

</asp:Content>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace WebApplication5
{
    public struct Book
    {
        public string title
        {
            get;
            set;
        }
        public string author
       {
            get;
            set;
        }
    }

    public partial class _Default : System.Web.UI.Page
    {
        protected List<Book> GridViewBooks
        {
            get
            {
                return (List<Book>)Session["Books"];
            }
            set
            {
                Session["Books"] = value;
            }
        }

        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                List<Book> theBooks = new List<Book>();
                Book aBook = new Book();
                aBook.title = "First book title";
                aBook.author = "First book author";

                theBooks.Add(aBook);

                GridViewBooks = theBooks;
                BindGrid();
            }

        }

        protected void RadButton1_Click(object sender, EventArgs e)
        {
            List<Book> theBooks = new List<Book>();
            Book aBook = new Book();
            aBook.title = "Another title " + DateTime.Now.ToString();
            aBook.author = "another book author";

            theBooks = GridViewBooks;
            theBooks.Add(aBook);
            GridViewBooks = theBooks;

            BindGrid();
        }

        private void BindGrid()
        {
            //bind gridview
            RadGrid1.DataSource = GridViewBooks;
            RadGrid1.DataBind();
        }

    }
}

Thanks for your help

[JD Emmert]

Also I forgot to mention that I've tried the NeedDataSource event and ReBind().  Also know as "advanced radgrid databinding."

[JD Emmert]

Well, I found out that you can place the button inside of a panel with the radgrid and place in the RadManager that the panel updates the panel and it works.  However this is not a solution for me as in reality, the button is no where near the gridview.  Why does this work?  Shouldn't I be able to say "this button updates that gridview (plus other controls if needed)," no matter where they are on the page?

[Radoslav]

Hi JD Emmert,

I am sending you a simple example which demonstrates the desired functionality. Into it I use the NeedDataSource event in order to bind the RadGrid:

void RadGrid1_NeedDataSource(object sender, Telerik.Web.UI.GridNeedDataSourceEventArgs e)
{
    RadGrid1.DataSource = GridViewBooks;
}

Into the Page_Load event one item is inserted into the GridViewBooks collection. This will guarantee that  when the page is loaded for the first time the grid is bound to one item:

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
         List<Book> theBooks = new List<Book>();
         Book aBook = new Book();
         aBook.title = "First book title";
         aBook.author = "First book author";
         theBooks.Add(aBook);
         GridViewBooks = theBooks;
    }
}

Then on RadButton1_Click event handler a new item is inserted into the GridViewBooks collection and the RadGrid is rebound. Calling the Rebind() method will force the RadGrid to fire its NeedDataSource event.

protected void RadButton1_Click(object sender, EventArgs e)
{
    List<Book> theBooks = new List<Book>();
    Book aBook = new Book();
    aBook.title = "Another title " + DateTime.Now.ToString();
    aBook.author = "another book author";
     theBooks = GridViewBooks;
     theBooks.Add(aBook);
     GridViewBooks = theBooks;

     RadGrid1.Rebind();
}

I hope this helps.

All the best,
Radoslav
the Telerik team