Hi

I want to bind a RadComboBox to the llblgendatasource2 control. I have just started with llblgen and web development so bear with me. I am looking to create an AJAX based CRUD template using llblgen template studio, within which I am using telerik rad controls and dev express grid. Now to the point at hand, for the sake of simplifying I have a order table and a product table . When inserting or editing an order users will select a product by name (not ID) from a radcomboox using their built in on demand mechanism (On Demand mechanism - you can set a poll-server timeout and the combobox fires a server-side event (ItemsRequested) that returns all the relative matches for the currently typed text). I am using on demand to reduce load time and unnecessary fetching of all the rows in the table which contains a vast amount of records. Now the following code is fine when not enclosed within a asp:FormView but when it is I receive the following error:

Databinding methods such as Eval(), XPath(), and Bind() can only be used in the context of a databound control.

Below is an Aspx snippet you may notice at present i’m working with an altered version of the ASP.NET 2.0 GUI generator templates).

<asp:FormView ID="frmEditOrders" DataKeyNames="OrderId" runat="server" 
    DefaultMode="insert" DataSourceID="_OrdersDS" Cellpadding="0" 
    OnItemCommand="frmEditOrders_ItemCommand" 
    OnItemCreated="frmEditOrders_ItemCreated">
<EditItemTemplate>
    <table cellpadding="3" border="0" cellspacing="1" class="formtexts">
        <tr>
            <td width="20"  nowrap="nowrap" class="content">&nbsp;</td>
            <td class="formtexts" >
                ProductId:
            </td>
            <td class="content">
            <llblgenpro:LLBLGenProDataSource2 ID="_ProductsDS" runat="server" 
                        DataContainerType="EntityCollection"  
    AdapterTypeName="SevenLayers.AdapterDataLayer.DatabaseSpecific.DataAccessAdapter, SevenLayers.AdapterDataLayerDBSpecific" EntityFactoryTypeName="SevenLayers.AdapterDataLayer.FactoryClasses.ProductsEntityFactory, SevenLayers.AdapterDataLayer"
                    LivePersistence="False"  onperformselect="_ProductsDS_PerformSelect" 
                    MaxNumberOfItemsToReturn="10" >
                    <SelectParameters>
                        <asp:ControlParameter ControlID="ddlProductId" Name="filterParameter" 
                            PropertyName="SelectedValue" />
                    </SelectParameters>
                </llblgenpro:LLBLGenProDataSource2>
                <telerik:RadComboBox ID="ddlProductId" Runat="server" SelectedValue='<%# Bind("ProductId") %>' 
                    DataSourceID="_ProductsDS" DataTextField="Name" DataValueField="ProductId" 
                    EnableLoadOnDemand="True" EnableVirtualScrolling="True" 
                    onitemsrequested="ddlProductId_ItemsRequested" ShowMoreResultsBox="true">
                <CollapseAnimation Type="OutQuint" Duration="200"></CollapseAnimation>  
                </telerik:RadComboBox>
            </td>
            <td width="20" nowrap="nowrap" class="content">&nbsp;</td>
        </tr>
    </table>
</EditItemTemplate>
</asp:FormView>

And sample code behind file:

   IRelationPredicateBucket filter = new RelationPredicateBucket();

    protected void _ProductsDS_PerformSelect(object sender, PerformSelectEventArgs2 e)
    {
        using (DataAccessAdapter adapter = new DataAccessAdapter())
        {
            adapter.FetchEntityCollection(e.ContainedCollection, filter, e.MaxNumberOfItemsToReturn, e.Sorter, e.PrefetchPath, e.PageNumber, e.PageSize);
        }
    }
    protected void ddlProductId_ItemsRequested(object o, Telerik.Web.UI.RadComboBoxItemsRequestedEventArgs e)
    {
        filter.PredicateExpression.Clear();
        RadComboBox combo = (RadComboBox)o;
        string queryString = e.Text + "%";
        PredicateExpression filterExpression = new PredicateExpression();
        filterExpression.AddWithAnd(ProductsFields.Name % queryString);
        filter.PredicateExpression.Add(filterExpression);
        combo.DataBind();
    }

Any help would be greatly appreciated. Thankyou.

V.2.6. .NET 3.5

I think your code should look like:

ASPX

<llblgenpro:LLBLGenProDataSource2 ID="_ProductsDS" runat="server"
     DataContainerType="EntityCollection"
     AdapterTypeName="SevenLayers.AdapterDataLayer.DatabaseSpecific.DataAccessAdapter, 
     SevenLayers.AdapterDataLayerDBSpecific" 
     EntityFactoryTypeName= "SevenLayers.AdapterDataLayer.FactoryClasses.ProductsEntityFactory, SevenLayers.AdapterDataLayer"
     LivePersistence="False" onperformselect="_ProductsDS_PerformSelect"
     MaxNumberOfItemsToReturn="10" >
</llblgenpro:LLBLGenProDataSource2>
                
<telerik:RadComboBox 
     ID="ddlProductId" Runat="server" 
     SelectedValue="ProductId"
     DataSourceID="_ProductsDS" 
     DataTextField="Name" 
     DataValueField="ProductId"
     EnableLoadOnDemand="True" 
     EnableVirtualScrolling="True"
     onitemsrequested="ddlProductId_ItemsRequested" ShowMoreResultsBox="true">
     <CollapseAnimation Type="OutQuint" Duration="200"></CollapseAnimation> 
</telerik:RadComboBox>

Note that you can't use Bind on a combo that is based on a dataSource that doesn't belong to the data context created by the surrounded FormView.

And, I would recommend you to use_ LivePersistence=true _as you are not doing anything special at PerformSelect.

Also, If you don't have many Products, why not only fetch them once. I think the ItemRequested you are using and the way you are binding would push many unnecessary times your server. IMHO you don't need code-behind here.

I also could recommend to you to review the ASP.Net DataBinding example at http://llblgen.com/pages/examples.aspx . That project has an Ajax example using LLBLGenProDataSource.