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RadComboBox LoadOnDemand unable to handle returning zero records

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ComboBox

This is a migrated thread and some comments may be shown as answers.

Micah Toland asked on 24 Jun 2010, 07:16 AM

I’m using a web service to feed the search as you type combo box on my page. If the search returns 0 results I get the following error:

Microsoft Jscript runtime error: ‘Items’ is null or not an object

It works fine if results are returned. Below is the code for the RadComboBox and below that is the web service method I’m using. Any assistance would be greatly appreciated.

Experienced this problem with both 2010 Q1 and now Q2 Beta.

RadComboBox Snippet:

<telerik:RadComboBox ID="rcmbClients" runat="server" EnableLoadOnDemand="true"
     ShowMoreResultsBox="true" EnableVirtualScrolling="true"
     TabIndex="1" EnableItemCaching="true" EnableViewState="false" EmptyMessage="-- enter text --"
     NoWrap="true" ShowWhileLoading="false"
     OnSelectedIndexChanged="rcmbClients_SelectedIndexChanged"
     AutoPostBack="true" Width="500" WebServiceSettings-Method="GetFilteredClients"
     Filter="Contains" ItemRequestTimeout="300" WebServiceSettings-Path="~/RadService.svc"
     AllowCustomText="true">
 </telerik:RadComboBox>

Web Service Snippet:

[ServiceContract(Namespace = "")]
 [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
 public class RadService
 {
  [OperationContract]
  public RadComboBoxData GetFilteredClients(RadComboBoxContext context)
  {
      try
      {
              
         RadComboBoxData result = new RadComboBoxData();
         ClientBL clientBL = new ClientBL();          IList<ShortClient> clients = clientBL.GetFilteredShortClients(context.Text.Replace("%", "[%]").Replace("&squote", "[']"));
         IEnumerable<RadComboBoxItemData> allDataItems = from client in clients

                                                         select new RadComboBoxItemData()

                                                         {

                                                             Text = client.DisplayName,

                                                             Value = client.ID.ToString()

                                                         };

         int numberOfItems = context.NumberOfItems;

         IEnumerable<RadComboBoxItemData> pageOfDataItems = allDataItems.Skip(numberOfItems).Take(500);

         result.Items = pageOfDataItems.ToArray();

         int endOffSet = numberOfItems + pageOfDataItems.Count();

         int totalCount = allDataItems.Count();

         if (endOffSet == totalCount)

             result.EndOfItems = false;

         result.Message = String.Format("Items <b>1</b>-<b>{0}</b> out of <b>{1}</b>", endOffSet, totalCount);

         return result;

     }

     catch (Exception ex)

     {

         string target = context.Text;

         LogManager logManager = new LogManager();

         logManager.Log(TraceEventType.Error, "Search Criteria Submitted By User: \"" + context.Text + "\""  + Environment.NewLine + ex.Message.ToString());

         throw;

     }

}

12 Answers, 1 is accepted

answered on 25 Jul 2010, 02:22 PM

Yes, it is strange, the control works perfectly until i type a value (last name) that returns 0 items. then i get the following error:

"Microsoft JScript runtime error: 'Items' is null or not an object" (Break/Continue/Ignore)

More details:
VS 2010
Project References: C:\Program Files (x86)\Telerik\RadControls for ASP.NET AJAX Q2 2010\Bin40\Telerik.Web.UI.dll (version 2010.2.713.40)
Cleared debug / release / bin folder and rebuilt project. that didn't help.

Sample Code:

web page:

  <telerik:RadScriptManager ID="RadScriptManager1" runat="server">
    </telerik:RadScriptManager>
    <div>
        <telerik:RadComboBox ID="RadComboBox1" runat="server" EnableLoadOnDemand="true" ShowMoreResultsBox="true"
            MarkFirstMatch="true" EmptyMessage="Type here...">
            <WebServiceSettings Method="GetClientList" Path="Services/ListService.svc" />
        </telerik:RadComboBox>
        <asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Button" />
        <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label><br />
        <select id="test">
        </select>
    </div>

Web Service:

  public class ListItem
        {
            public int ID { get; set; }
            public string Text { get; set; }
        }


  [OperationContract]

        public Telerik.Web.UI.RadComboBoxData GetClientList(Telerik.Web.UI.RadComboBoxContext context)

        {

            RadComboBoxData result = new RadComboBoxData()

            Model.DbContext db = new Model.DbContext();



            var allItems = (from d in db.Clients



                            orderby d.LastName

                            select new ListItem

                            {

                                ID = d.DirID,

                                Text = d.LastName

                            });



            string filter = context.Text;

            if (!String.IsNullOrEmpty(filter))

            {

                allItems = allItems.Where(d => d.Text.StartsWith(filter));

            }



            // perform the paging

            int numberOfItems = context.NumberOfItems;

            var items = allItems.Skip(numberOfItems).Take(10);



            // execute database query

            List<ListItem> tmpItems = items.ToList();

            result.Items = tmpItems.Select(d => new RadComboBoxItemData() { Text = d.Text, Value = d.ID.ToString() }).ToArray();



            int endOffset = numberOfItems + items.Count();

            int totalCount = allItems.Count();

            if (endOffset == totalCount) result.EndOfItems = true;



            //Initialize the status message

            result.Message = String.Format("Items <b>1</b>-<b>{0}</b> out of <b>{1}</b>", endOffset, totalCount);



            return result;

        }

answered on 29 Jul 2010, 02:57 PM

Hello B,

The Trial and Dev versions are exactly the same in terms of functionality.

I just verified the case with the latest version of Telerik.Web.UI and can confirm that it works properly. In this demo, I modified the WCF service to not set the Items property of the RadComboBoxData object and the RadComboBox handled this without an error on the client side.

Can you please open the HTML source of the page and search for '2010.' - this will show the version of Telerik.Web.UI which is actually used on the page?

Kind regards,
Simon
the Telerik team

Do you want to have your say when we set our development plans? Do you want to know when a feature you care about is added or when a bug fixed? Explore the Telerik Public Issue Tracking system and vote to affect the priority of the items

answered on 30 Jul 2010, 06:57 PM

Okay, here's my html page. Pretty simple...it's got the radcombo and a scriptmanager control. I did not find a reference to 2010. I also attached a version screenshot of the telerik.we.ui in my project reference...

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="CP.Web.WebForm1" %>
 
<!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></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <telerik:RadScriptManager ID="RadScriptManager1" runat="server">
        </telerik:RadScriptManager>
        
         <telerik:RadComboBox ID="RadComboBox1" runat="server" EnableLoadOnDemand="true" ShowMoreResultsBox="true"
            MarkFirstMatch="true" EmptyMessage="Type here...">
            <WebServiceSettings Method="GetClientList" Path="Services/ListService.svc" />
        </telerik:RadComboBox>
        
    </div>
    </form>
</body>
</html>