LoadOnDemand Issues

[iomega 55]

Hi:

I need to solve this issues on the combobox:

1) When I first load my page, the radcombobox doesnt load any item, it loads them just after the first callback on the page, a callback fired by another control different to the radcombobox. In the first try it shows just the "loading" message but it doesnt return any item.

2) How can I use the onselectindexchanged in the radcombobox using the loadondemand funcionality? I need to load a labels and textboxes after the selectedvalued is changed on the radcombobox, but this event is never fired.

3) I have a master page, in which I have defined a RadScriptManager, RadAjaxLoadingPanel, RadAjaxPanel

4) Inside the RadAjaxPanel, I have a contentplaceholder.

5) In my content pages I have defined a radcombobox like this:

<telerik:RadComboBox ID="cmbUC" runat="server" Height="230px" Width="230px"

DropDownWidth="215px" EmptyMessage="Select an UC" HighlightTemplatedItems="true"

EnableLoadOnDemand="true" OnItemsRequested="cmbUC_ItemsRequested" ShowWhileLoading="true">

<HeaderTemplate>

<table style="width: 200px" cellspacing="0" cellpadding="0">

<tr>

<td style="width: 40px;">

Plates</td>

<td style="width: 160px;">

UC</td>

</tr>

</table>

</HeaderTemplate>

<ItemTemplate>

<table style="width: 200px" cellspacing="0" cellpadding="0">

<tr>

<td style="width: 40px;">

<%# DataBinder.Eval(Container, "Text")%>

</td>

<td style="width: 160px;">

<%# DataBinder.Eval(Container, "Attributes['uc']")%>

</td>

</tr>

</table>

</ItemTemplate>

</telerik:RadComboBox>

<asp:RequiredFieldValidator runat="server" ID="RequiredFieldValidator1" ControlToValidate="cmbUC"

ErrorMessage="!" CssClass="validator">

</asp:RequiredFieldValidator>

In the server side:

    protected void cmbUC_ItemsRequested(object sender, RadComboBoxItemsRequestedEventArgs e)
    {
        Tbl01UCCollection _uccollection = new Tbl01UCCollection();

        _uccollection = cTbl01UC.UnidadCargaCollectionLoadFilter(Convert.ToInt32(Session["sesCompany"]), e.Text);

        foreach (Tbl01UC _uc in _uccollection)
        {
            RadComboBoxItem item = new RadComboBoxItem();

            item.Text = _uc.Plates;
            item.Value = _uc.Rowid.ToString();

            item.Attributes.Add("uc", _uc.Descripcion);

            cmbUCItems.Add(item);

            item.DataBind();
        }
    }

[iomega 55]

Sorry, I found the error.

Due to the huge viewstate that telerik's controls generate, I add this to the basepage class I used:

    protected override void Render(HtmlTextWriter writer)
    {
        StringWriter stringWriter = new StringWriter();
        HtmlTextWriter htmlWriter = new HtmlTextWriter(stringWriter);
        base.Render(htmlWriter);

        string html = stringWriter.ToString();
        int StartPoint;
        int SLength;
        string ViewStateInput = "";
        StartPoint = html.IndexOf("<input type=\"hidden\" name=\"__VIEWSTATE\"");
        if (StartPoint >= 0)
        // does __VIEWSTATE exist?
        {
            SLength = html.IndexOf("/>", StartPoint) + 2 - StartPoint;
            ViewStateInput = html.Substring(StartPoint, SLength);
            html = html.Remove(StartPoint, SLength);
            int FormEndStart = html.IndexOf("</form>");
            html = html.Insert(FormEndStart, ViewStateInput);
        }

        writer.Write(html);
    }

This makes my pages display faster even if the viewstate is huge. This code moves the viewstate variable from the top to the bottom of the page.

If I have a radcombobox and in the page  I have more than 10 webcontrols, the first load of the radcombobox returns an error(500 internal server error). So I need a first callback and later the radcombobox works ok.

I deleted these code from my basepage and the radcombobox works in the normal way :) :(

Any comment is welcomed.

[Simon]

Hello iomega 55,

In order to inspect the first issue I tried first recreating it on a page with 10 GridViews and the Render method override you provided. The RadComboBox made its first and all subsequent Load On Demand requests successfully. I attached the test page to this post so that you see it as well. Can you see it and let me know if I am missing something?

Regarding the second issue, you need to set the AutoPostBack property of the RCB to true so that it automatically posts back the page and raise its server-side event.

Greetings,
Simon
the Telerik team

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