Radgrid export in Custom Control

[Gooya]

Hello
I created custom control to list some data from database. I used radgrid for this. Now everything works fine, except exporting.
When I click export button GvExpertise_ItemCommand is triggered and columns are set hidden. But after that exception is triggered:

The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.Web.HttpException: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Source Error: 

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace: 

[HttpException (0x80004005): The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).] System.Web.UI.ControlCollection.Add(Control child) +9601391 Telerik.Sitefinity.Web.SitefinityRequiredControls.Page_PreRenderComplete(Object sender, EventArgs e) +521 System.EventHandler.Invoke(Object sender, EventArgs e) +0 System.Web.UI.Page.OnPreRenderComplete(EventArgs e) +121 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1155

---

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.17929


Codefile:

public class ExpertiseListView : SimpleView

   {

       #region control info

       public static Guid GroupPageGuid = new Guid("6743bffb-7cce-4e5c-9d9e-fc7ff1fa5e73");

       public static Guid PageGuid = new Guid("f0608080-5054-48b7-8218-a72ac6842e40");

       public static string TemplateName = "ContactsFormModule.Resources.Backend.ExpertiseListView.ascx";

       protected override string LayoutTemplateName { get { return TemplateName; } }

       #endregion

 

       #region controls

       protected virtual ITextControl LblTitle { get { return base.Container.GetControl<ITextControl>("LblTitle", true); } }               

       protected virtual HyperLink BtnAdd { get { return base.Container.GetControl<HyperLink>("BtnAdd", true); } }     

       protected virtual RadGrid GvExpertise { get { return base.Container.GetControl<RadGrid>("GvExpertise", true); } }

       #endregion

 

       public static string FieldName(bool isGeneral, bool isCompany)

       {

           if (isGeneral && isCompany)

               return "...";

           else if (isGeneral)

               return "..";

           else if (isCompany)

               return ".";

           else

               return string.Empty;

       }

 

       protected override void InitializeControls(GenericContainer container)

       {

           LblTitle.Text = "Expertise";

           LblAdd.Text = "Dodaj";

           //BtnAdd.NavigateUrl = App.WorkWith().Page(ExpertiseEditView.PageGuid).Get().GetFullUrl();

         

           GvExpertise.NeedDataSource += GvExpertise_NeedDataSource;

            

           GvExpertise.ItemCommand += GvExpertise_ItemCommand;

           GvExpertise.ItemDataBound += GvExpertise_ItemDataBound;

       }

 

       void GvExpertise_NeedDataSource(object sender, GridNeedDataSourceEventArgs e)

       {

           GvExpertise.DataSource = new ContactsManager().Expertises;

       }

 

       void GvExpertise_ItemDataBound(object sender, GridItemEventArgs e)

       {

           if (e.Item is GridDataItem)

           {

               ((LinkButton)((GridDataItem)e.Item)["DeleteColumn2"].Controls[0]).Text = ((Expertise)e.Item.DataItem).IsVisible ? "skrij" : "prikaži";

               ((Literal)((GridDataItem)e.Item)["Field"].Controls[0]).Text = FieldName(((Expertise)e.Item.DataItem).General,((Expertise)e.Item.DataItem).Company);

           }

       }

 

       void GvExpertise_ItemCommand(object sender, GridCommandEventArgs e)

       {

           if (e.CommandName == "hide")

           {

               int iId = (int)((GridDataItem)e.Item).GetDataKeyValue("Id");

               ContactsManager dataContext = new ContactsManager();

               Expertise expertise = dataContext.Expertises.FirstOrDefault(x => x.Id == iId);

               expertise.IsVisible = !expertise.IsVisible;

               dataContext.SaveChanges();

               GvExpertise.DataSource = new ContactsManager().Expertises;

               this.GvExpertise.DataBind();

           }

           else if (e.CommandName == RadGrid.ExportToCsvCommandName || e.CommandName == RadGrid.ExportToExcelCommandName || e.CommandName == RadGrid.ExportToPdfCommandName)

           {

               GvExpertise.MasterTableView.Columns[3].Visible = false;

               GvExpertise.MasterTableView.Columns[4].Visible = false;

 

           }

       }

   }



Template:

<div class="sfWorkArea">
                <div class="sfMessage sfGridViewMessage"><asp:Literal id="LblMessage" runat="server"></asp:Literal></div>
                <div>
                    <div class="RadGrid RadGrid_Sitefinity rgTopOffset" tabindex="0">
                        <telerik:RadAjaxManager ID="RadAjaxManager1" runat="server">
                            <AjaxSettings>
                                <telerik:AjaxSetting AjaxControlID="RadGrid1">
                                    <UpdatedControls>
                                        <telerik:AjaxUpdatedControl ControlID="GvExpertise" />
                                    </UpdatedControls>
                                </telerik:AjaxSetting>
                            </AjaxSettings>
                        </telerik:RadAjaxManager>
                        <telerik:RadGrid ID="GvExpertise" runat="server" AllowPaging="True"
                            AllowSorting="True" AutoGenerateColumns="False" CellPadding="0" Width="100%"
                            DataKeyNames="Id"
                            GridLines="None" PageSize="30" EnableModelValidation="True" Skin="Sitefinity">
                            <ExportSettings ExportOnlyData="True" IgnorePaging="True" OpenInNewWindow="True" HideStructureColumns="true">
                                <Excel Format="Biff"></Excel>
                                <Csv ColumnDelimiter="Semicolon" RowDelimiter="NewLine" EncloseDataWithQuotes="true" FileExtension=".csv" />
                            </ExportSettings>
                            <MasterTableView DataKeyNames="Id" CommandItemDisplay="Top">
                                <CommandItemSettings ShowAddNewRecordButton="false" ShowExportToExcelButton="true" ShowExportToCsvButton="true"/>
                                <Columns>
                                    <telerik:GridBoundColumn DataField="Id" HeaderText="Id" SortExpression="Id" />
                                    <telerik:GridBoundColumn DataField="Description" HeaderText="Strokovno znanje" SortExpression="Description" />
                                    <telerik:GridTemplateColumn DataField="Company,General" SortExpression="Company,General" UniqueName="Field"><ItemTemplate><asp:Literal runat="server" ID="LblField" /></ItemTemplate></telerik:GridTemplateColumn>
                                    <telerik:GridHyperLinkColumn DataNavigateUrlFields="Id" />
                                    <telerik:GridButtonColumn Text='' ButtonType="LinkButton" CommandName="hide"  UniqueName="DeleteColumn2"><HeaderStyle Width="20px"></HeaderStyle></telerik:GridButtonColumn>
                                </Columns>
                            </MasterTableView>
                        </telerik:RadGrid>
                    </div>
                </div>
            </div>

ViewState is on, and radscriptmanager exists on page.

[Kostadin]

Hi Mitja,

If you have any code blocks you can enclose them using telerik:RadCodeBlock tag. Additionally I noticed that your grid is ajaxified. Note that the exporting feature works only with regular postbacks. This means, that the asynchronous postback should be canceled when performing an export.

More information on this topic is available below:
Export from ajaxified grid
Exclude controls from ajaxifying
Export RadGrid content to Excel/Word/CSV/PDF with Ajax enabled

All the best,
Kostadin
the Telerik team