RADComboBox in Grid

[Giancarlo]

Hi Forum,
I have a RADGrid with a RADComboBox column with EnableLoadOnDemand=true and ItemsRequest event defined.

<telerik:RadComboBox ID="cboLocalita"

EnableVirtualScrolling="true"

OnItemsRequested="cboLocalita_ItemsRequested"

ShowMoreResultsBox="true"

EnableLoadOnDemand="true"

DataTextField ="descrizione"

DataValueField ="idlocalita"

runat="server">

</telerik:RadComboBox>

Protected Sub cboLocalita_ItemsRequested(ByVal o As Object, ByVal e As Telerik.Web.UI.RadComboBoxItemsRequestedEventArgs)
    Dim context As New JLogTabelleDataContext
    Dim allLocalita = From localita In context.localita _
     Order By localita.descrizione _
     Select localita
    If Not [String].IsNullOrEmpty(e.Text) Then
        allLocalita = From localita In context.localita _
         Where localita.descrizione.StartsWith(e.Text) _
         Order By localita.descrizione _
         Select localita
    End If
    Dim Lstlocalita = allLocalita.Skip(e.NumberOfItems).Take(10)
    CType(o, RadComboBox).DataSource = Lstlocalita
    CType(o, RadComboBox).DataBind()
    Dim endOffset As Integer = e.NumberOfItems + Lstlocalita.Count()
    Dim totalCount As Integer = allLocalita.Count()
    If endOffset = totalCount Then
        e.EndOfItems = True
    End If
    e.Message = [String].Format("Rec <b>1</b>-<b>{0}</b> Tot <b>{1}</b>", endOffset, totalCount)
End Sub

The automatic CRUD operation enabled on the Grid doesn't work, so the value of RADComboBox never change after update of then EditForm and is setted to NULL when I perform a created operation.

If I bind the Combobox to a Datasource object by the property DataSourceID and I disable EnableLoadOnDemand without implement OnItemsRequest event , CRUD works fine. I have a lot of records to show in ComboBox therefore Loading data on demand is very important.
Thanks to all for any response.
Gaetano

[Tsvetina]

Hi Gaetano,

By default, there is no problem with using load on demand RadComboBox in RadGrid with automatic operations. You can see how this is implemented here:
Grid / Combo in Grid
If you do not notice any differences, you can consider opening a support ticket and sending us the full code related to this scenario.

Regards,
Tsvetina
the Telerik team

[Giancarlo]

Hi,
I bind RADComboBox to property "idlocalita" of the RADGrid's datasource.
At run time an exception occurs:    Selection out of range Nome parametro: value
The datasource of RadCombo is not defined declarative by property DatasourceID but in order to take advantage of the LoadOnDemand capability I defined event : onItemsRequested 
Is This the correct way?

below my aspx tag

<telerik:GridTemplateColumn DataField="localita.descrizione" HeaderText="Località" SortExpression="localita.descrizione" >
                    <HeaderStyle Width="25%" />
                    <ItemTemplate>
                        <%#Eval("localita.descrizione")%>
                    </ItemTemplate>
                    <EditItemTemplate>
                        <telerik:RadComboBox ID="cboLocalita"
                            SelectedValue='<%# bind("idlocalita") %>'
                            OnItemsRequested ="cboLocalita_ItemsRequested"
                            EnableVirtualScrolling="true"
                            ShowMoreResultsBox="true"
                            EnableLoadOnDemand="true"
                            DataTextField ="descrizione"
                            DataValueField ="idlocalita"
                            runat="server">
                        </telerik:RadComboBox>
                    </EditItemTemplate>
                </telerik:GridTemplateColumn>

my vb code:

Protected Sub cboLocalita_ItemsRequested(ByVal o As Object, ByVal e As Telerik.Web.UI.RadComboBoxItemsRequestedEventArgs)

    Dim context As New JLogTabelleDataContext

    Dim allLocalita = From localita In context.localita _
     Order By localita.descrizione _
     Select localita

    If Not [String].IsNullOrEmpty(e.Text) Then
        allLocalita = From localita In context.localita _
         Where localita.descrizione.StartsWith(e.Text) _
         Order By localita.descrizione _
         Select localita
    End If

    Dim Lstlocalita = allLocalita.Skip(e.NumberOfItems).Take(10)
    CType(o, RadComboBox).DataSource = Lstlocalita
    CType(o, RadComboBox).DataBind()

    Dim endOffset As Integer = e.NumberOfItems + Lstlocalita.Count()
    Dim totalCount As Integer = allLocalita.Count()

    If endOffset = totalCount Then
        e.EndOfItems = True
    End If

    e.Message = [String].Format("Rec <b>1</b>-<b>{0}</b> Tot <b>{1}</b>", endOffset, totalCount)

End Sub

[Tsvetina]

Hi Gaetano,

You cannot declaratively set SelectedValue to the combo when you bind it on demand. This way it looks for a value initially that is not available (it has no items when the grid is put in edit mode). The correct approach would be to remove the SelectedValue setting from mark-up and do the selection manually only after you bind the combo in ItemsRequested event.

Regards,
Tsvetina
the Telerik team