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[Solved] LoadOnDemand doesn't show any entries

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ComboBox

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Torben asked on 20 Aug 2009, 02:01 PM

Hi,

I'm trying to implement a combobox which should dynamically load and display some data from a xml-file.
In debugger I can see that the data is loaded correctly and is added to the combobox-control via RadComboBox1.Items.Add(...).

But afterwards nothing is displayed in the combobox - the box still remains displaying "Loading..."

The Data I'm expecting is:
"", "" (empty Strings)
"data1", "data1"
"data2", "data2"
"data3", "data3"
"data4", "data4"

Here's the code of the combobox-control in my .aspx-file:

    
            <telerik:RadComboBox ID="RadComboBox1" runat="server" AllowCustomText="True" EmptyMessage="Choose Data" EnableLoadOnDemand="True" ShowMoreResultsBox="true" 
        
            EnableVirtualScrolling="true" Filter="StartsWith" AutoPostBack="True" DataTextField="Name" DataValueField="Name"> 
        
            </telerik:RadComboBox>

Here is what is done on the server in my .aspx.vb-file:

    
            Protected Sub RadComboBox1_ItemsRequested(ByVal sender As Object, ByVal e As RadComboBoxItemsRequestedEventArgs) Handles RadComboBox1.ItemsRequested 
        
                    Dim data As DataTable = GetData(e.Text) 
        
                    Dim itemOffset As Integer = e.NumberOfItems 
        
                    Dim endOffset As Integer = Math.Min(itemOffset + ItemsPerRequest, data.Rows.Count) 
        
                    e.EndOfItems = endOffset = data.Rows.Count 
        
                    For i As Integer = 0 To data.Rows.Count - 1 
        
                        RadComboBox1.Items.Add(New RadComboBoxItem(data.Rows(i)("Name").ToString(), data.Rows(i)("Name").ToString())) 
        
                    Next 
        
                    e.Message = GetStatusMessage(endOffset, data.Rows.Count) 
        
                End Sub

Does somebody has an idea or hint on what I'm doing wrong?

Kind regards,
Torben

5 Answers, 1 is accepted

answered on 21 Aug 2009, 08:08 PM

Hi Yana,

I think I figured it out.
I had to ensure that there is no other Content-Output before "RadAjaxPanel". Before, I wether not used "RadAjaxPanel" or it has been included after something was output.

This won't work for me:

    
            <%@ Master Language="VB" CodeFile="default_ajax.master.vb"  Inherits="ajax_internal_MasterPage"%> 
        
            <%@ Register Assembly="Telerik.Web.UI" Namespace="Telerik.Web.UI" TagPrefix="telerik" %> 
        
            <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 
        
            <body>  
        
                <form id="form1" runat="server">  
        
                <telerik:RadScriptManager ID="RadScriptManager1" runat="server" />  
        
                    <div class="menu">  
        
                        My Main-Menu-Content  
        
                    </div>  
        
                    <div style="margin:2px; margin-top:5px; vertical-align:top;"> 
        
                      <!-- content start -->  
        
                      <telerik:RadAjaxPanel runat="server" ID="RadAjaxPanel1">   
        
                            <asp:contentplaceholder id="ContentPlaceHolder1" runat="server">  
        
                            </asp:contentplaceholder> 
        
                      </telerik:RadAjaxPanel> 
        
                      <!-- content end --> 
        
                    </div>  
        
                </form>  
        
            </body>

So my MasterPage has to look something like this to work correctly for me:

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

            <%@ Register Assembly="Telerik.Web.UI" Namespace="Telerik.Web.UI" TagPrefix="telerik" %>

            <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

            <body> 
        
                <form id="form1" runat="server"> 
        
                <telerik:RadScriptManager ID="RadScriptManager1" runat="server" /> 
        
                <!-- content start --> 
        
                <telerik:RadAjaxPanel runat="server" ID="RadAjaxPanel1"> 
        
                    <div class="menu"> 
        
                        My Main-Menu-Content 
        
                    </div> 
        
                    <div style="margin:2px; margin-top:5px; vertical-align:top;"> 
        
                            <asp:contentplaceholder id="ContentPlaceHolder1" runat="server"> 
        
                            </asp:contentplaceholder> 
        
                    </div> 
        
                </telerik:RadAjaxPanel> 
        
                <!-- content end --> 
        
                </form> 
        
            </body>

Torben

answered on 24 Aug 2009, 01:20 PM

Hi Torben,

This is strange, RadAjax panel should work even if there's output content before it, but you shouldn't use Loan-On-Demand mechanism of RadComboBox along with RadAjax, you should entirely use the combobox in a server mode - adding the items in the Load event of the page for instance. The AJAX Panel will take care of transforming the postback into a callback and thus keeping the needed client-side experience.

Best wishes,
Yana
the Telerik team

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