ASP.NET

protected void RefreshDropDownList(object sender, EventArgs e)
    {
        if (((RadioButtonList)sender).SelectedValue == "1")
        {
            if (odsAreasCU.SelectMethod != "GetAreasPubProyecto")
            {
                DropDownList ddl = ((DropDownList)dvCU.FindControl("DropDownList20"));
                ddl.DataSourceID = odsNewObjetDataSource.ID;
                ddl.DataTextField = "Name";
                ddl.DataValueField = "CodObj";
                ddl.DataBind();
            }            
        }
        else //if (((RadioButtonList)sender).SelectedValue == "2")
        {
              //...
        }
    }

<asp:TemplateField HeaderText="Area" SortExpression="Area">
    <EditItemTemplate>
        <asp:DropDownList ID="DropDownList20" runat="server" DataSourceID="odsAreasCU"
            DataTextField="Nombre" DataValueField="CodObj" ForeColor="#006666"
            SelectedValue= '<%#DataBinder.Eval(Container.DataItem,"Area")%>'
            Width="200px" ondatabinding="DropDownList20_DataBinding"
            ondatabound="DropDownList20_DataBound"
            onselectedindexchanged="DropDownList20_SelectedIndexChanged1"
            AppendDataBoundItems="True">
            <asp:ListItem Value="0">(sin área específica)</asp:ListItem>
        </asp:DropDownList>
    </EditItemTemplate>