CODEWITHSUNDEEP
asp.netdatagridview
Harshit
Harshit

Reputation: 5157

VerifyRenderingInServerForm : no suitable method found to override C# error

I am writing a code to export to excel a gridview. I am using updatepanel, so whole page doesnot loads. So, i wrote a code :

aspx.cs Code

protected void Export_click(object sender, EventArgs e)
    {
        GridView gv = (GridView)TBMMasterContentPalceHolder.FindControl("myGridView");
        Response.Clear();
        Response.AddHeader("content-disposition", "attachment;filename=Suppliers.xls");
        Response.Charset = "";
        Response.ContentType = "application/vnd.xls";
        System.IO.StringWriter stringWrite = new System.IO.StringWriter();
        System.Web.UI.HtmlTextWriter htmlWrite = new HtmlTextWriter(stringWrite);
        gv.RenderControl(htmlWrite);
        Response.Write(stringWrite.ToString());
        Response.End();

    }
    public override void VerifyRenderingInServerForm(Control control) //To prevent Export To Excel Error
    {
    }

asp Code

<asp:Button ID="btnExport" runat="server" Text="  Export  " OnClick="Export_click" />
<Triggers>
        <asp:PostBackTrigger ControlID="btnExport" />
</Triggers>

But here, i am getting the error in VerifyRenderingInServerForm(Control control) function. Error is :

VerifyRenderingInServerForm(System.Web.UI.Control)': no suitable method found to override

How to solve the error ?

Upvotes: 2

Views: 6644

Answers (3)

AxleWack
AxleWack

Reputation: 1911

Thank you!

I have been searching for a solution for quite sometime. I looked over your code before and I couldnt seem to get it working - But this was because of a lack of knowledge. So for anyone else that might sit with this same problem, here was my scenario and solution, please note that this is in VB and can be converted using any online converting tool :

Scenario : I have a master page with an export button which exports data from a gridview on a page using the masterpage.

In the Page_Load event of the page with the Gridview, i used the following code :

Dim myMasterPage As MasterPageName = Page.Master

Dim exportButton As System.Web.UI.WebControls.Button = myMasterPage.FindControl("ButExportExcel")

If (exportButton IsNot Nothing) Then 
    AddHandler exportButton.Click, AddressOf Me.ButExportExcel_Click
End If

I then created the public sub:

Private Sub ButExportExcel_Click(ByVal sender As Object, ByVal e As System.EventArgs)

    Dim sMethod = "ButExportExcel_Click"
    Dim sErrorMessage = ""
    Dim sExportFileName As String = ""

    Try

        sExportFileName = Path.GetFileName(Request.PhysicalPath)
        sExportFileName = sExportFileName.Substring(0, sExportFileName.Length - 5) & ".xls"

        Response.Clear()
        Response.AddHeader("content-disposition", "attachment; filename=" & sExportFileName)
        Response.ContentType = "application/vnd.xls"
        Dim WriteItem As System.IO.StringWriter = New System.IO.StringWriter()
        Dim htmlText As System.Web.UI.HtmlTextWriter = New HtmlTextWriter(WriteItem)
        SummaryGridView.AllowPaging = False
        'Dim dtSupplier As DataTable = CType(ViewState("dtSupplier"), DataTable)
        'SummaryGridView.DataSource = dtSupplier
        SummaryGridView.DataBind()
        SummaryGridView.RenderControl(htmlText)
        Response.Write(WriteItem.ToString())
        Response.End()

    Catch ex As Exception



    End Try
End Sub

Then adding the below :

Public Overrides Sub VerifyRenderingInServerForm(control As Control)
End Sub

This unfortunately means it needs to go onto every page that you want a gridview to be exported from, but it did the job for me. This only exports the data in the gridview.

I hope this helps anyone who is sitting with the same problem.

Upvotes: 0

Tim Schmelter
Tim Schmelter

Reputation: 460238

As commented the class is a MasterPage not a Page, that's why there is no method to override VerifyRenderingInServerForm. A MasterPage inherits from UserControl and behaves like one.

So you have to move this code to the page. If that's not possible you should use event-driven communication to trigger the export functionality from master.

  • Add an event to the master page.
  • Raise the event whenever the master page needs to communicate with its content page. In this case in the button-click event handler
  • Create an event handler in those content pages that need to take some action. In this case the export functionality

http://www.asp.net/web-forms/overview/older-versions-getting-started/master-pages/interacting-with-the-content-page-from-the-master-page-cs

Upvotes: 1

Harshit
Harshit

Reputation: 5157

I got my answer. Remove VerifyRenderingInServerForm(Control control) function & use 

System.Web.UI.HtmlControls.HtmlForm form = new System.Web.UI.HtmlControls.HtmlForm();
            Controls.Add(form);
            form.Controls.Add(gv);
            form.RenderControl(htmlWrite);

So, our final code would be

Response.Clear();
            Response.AddHeader("content-disposition", "attachment;filename=myfile.xls");
            Response.Charset = "";
            Response.ContentType = "application/vnd.xls";
            System.IO.StringWriter stringWrite = new System.IO.StringWriter();
            System.Web.UI.HtmlTextWriter htmlWrite = new HtmlTextWriter(stringWrite);

            System.Web.UI.HtmlControls.HtmlForm form = new System.Web.UI.HtmlControls.HtmlForm();
            Controls.Add(form);
            form.Controls.Add(gv);
            form.RenderControl(htmlWrite);
            Response.Write(stringWrite.ToString());
            Response.End();

Upvotes: 4

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