Solved

Export Gridview to Excel Produces Blank XLS file - Gridview Inside Update Panel...

Posted on 2009-07-13
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Last Modified: 2012-05-07
I have used this export code in a number of places with no problem, but now that the gridview is located inside an UpdatePanel, I'm getting blank excel sheets when it exports.

Where am I dropping the data?  I debugged and in the BtnExportGrid_Click subroutine, the gvProd gridview has a 0 row count, so it's dropping the data somewhere before it even gets into the GridViewExportUtil class.

Thanks for any ideas!
<asp:UpdatePanel ID="updList" runat="server">

                        <ContentTemplate>
 

<tr>

                    <td colspan="2">

                        <br />

                        <asp:Panel ID="pnlFilter" runat="server" CssClass="TextLabel" OnClick="LetterChanged">

                                <asp:LinkButton ID="lnk0" runat="server" Text="[0-9]" ></asp:LinkButton> 

                                <asp:LinkButton ID="lnkA" runat="server" Text="A" AutoPostBack="True"></asp:LinkButton>                                                                                                                    

                                <asp:LinkButton ID="lnkB" runat="server" Text="B" AutoPostBack="True"></asp:LinkButton>                                                                                                                    

                                <asp:LinkButton ID="lnkC" runat="server" Text="C" AutoPostBack="True"></asp:LinkButton>                                                                                                                    

                                <asp:LinkButton ID="lnkD" runat="server" Text="D" AutoPostBack="True"></asp:LinkButton>                                                                                                                    

                                <asp:LinkButton ID="lnkE" runat="server" Text="E" AutoPostBack="True"></asp:LinkButton>                                                                                                                    

                                <asp:LinkButton ID="lnkF" runat="server" Text="F" AutoPostBack="True"></asp:LinkButton>                                                                                                                    

                                <asp:LinkButton ID="lnkG" runat="server" Text="G" AutoPostBack="True"></asp:LinkButton>                                                                                                                    

                                <asp:LinkButton ID="lnkH" runat="server" Text="H" AutoPostBack="True"></asp:LinkButton>                                                                                                                    

                                <asp:LinkButton ID="lnkI" runat="server" Text="I" AutoPostBack="True"></asp:LinkButton>                                                                                                                    

                                <asp:LinkButton ID="lnkJ" runat="server" Text="J" AutoPostBack="True"></asp:LinkButton>                                                                                                                    

                                <asp:LinkButton ID="lnkK" runat="server" Text="K" AutoPostBack="True"></asp:LinkButton>                                                                                                                    

                                <asp:LinkButton ID="lnkL" runat="server" Text="L" AutoPostBack="True"></asp:LinkButton>                                                                                                                    

                                <asp:LinkButton ID="lnkM" runat="server" Text="M" AutoPostBack="True"></asp:LinkButton>                                                                                                                    

                                <asp:LinkButton ID="lnkN" runat="server" Text="N" AutoPostBack="True"></asp:LinkButton>                                                                                                                    

                                <asp:LinkButton ID="lnkO" runat="server" Text="O" AutoPostBack="True"></asp:LinkButton>                                                                                                                    

                                <asp:LinkButton ID="lnkP" runat="server" Text="P" AutoPostBack="True"></asp:LinkButton>                                                                                                                    

                                <asp:LinkButton ID="lnkQ" runat="server" Text="Q" AutoPostBack="True"></asp:LinkButton>                                                                                                                    

                                <asp:LinkButton ID="lnkR" runat="server" Text="R" AutoPostBack="True"></asp:LinkButton>                                                                                                                    

                                <asp:LinkButton ID="lnkS" runat="server" Text="S" AutoPostBack="True"></asp:LinkButton>                                                                                                                    

                                <asp:LinkButton ID="lnkT" runat="server" Text="T" AutoPostBack="True"></asp:LinkButton>                                                                                                                    

                                <asp:LinkButton ID="lnkU" runat="server" Text="U" AutoPostBack="True"></asp:LinkButton>                                                                                                                    

                                <asp:LinkButton ID="lnkV" runat="server" Text="V" AutoPostBack="True"></asp:LinkButton>                                                                                                                    

                                <asp:LinkButton ID="lnkW" runat="server" Text="W" AutoPostBack="True"></asp:LinkButton>                                                                                                                    

                                <asp:LinkButton ID="lnkX" runat="server" Text="X" AutoPostBack="True"></asp:LinkButton> 

                                <asp:LinkButton ID="lnkY" runat="server" Text="Y" AutoPostBack="True"></asp:LinkButton> 

                                <asp:LinkButton ID="lnkZ" runat="server" Text="Z" AutoPostBack="True"></asp:LinkButton> 

                                <asp:LinkButton ID="lnkAll" runat="server" Text="ALL" AutoPostBack="True"></asp:LinkButton>

					  <asp:Button ID="btnExportGrid" runat="server" CssClass="TextLabel" Text="Export List" ForeColor="Green" Height="22" OnClick="BtnExportGrid_Click" />

                        </asp:Panel>
 

                        <asp:Panel ID="pnlProdList" runat="server" Height="300px" Width="800px" ScrollBars="both">

                            <asp:HiddenField ID="hdnLetter" runat="server" />

                            <asp:GridView ID="gvProd" runat="server" BackColor="#EEEEEE" GridLines="horizontal" AllowSorting="false" CssClass="TextLabel" Width="780px"

                                AutoGenerateColumns="false" DataKeyNames="key" EnableViewState="false" >

                                <SelectedRowStyle BackColor="LightYellow" Font-Bold="true" />

                                <HeaderStyle BackColor="LightSlateGray" ForeColor="White" />

                                <AlternatingRowStyle BackColor="#DDDDDD" Font-Bold="false" />

                                <RowStyle Font-Bold="false" />                                

                                <Columns>                                                                        

                                    <asp:CommandField SelectText="Details." ShowSelectButton="true" />

                                    <asp:BoundField DataField="prodname" HeaderText="Name" SortExpression="prod" />

                                </Columns>                                                        

                            </asp:GridView>

                        </asp:Panel>

                       </ContentTemplate>

                        <Triggers>

                       <Triggers>

                          <asp:AsyncPostBackTrigger ControlID="lnk0" EventName="Click"></asp:AsyncPostBackTrigger>

                          <asp:AsyncPostBackTrigger ControlID="lnkA" EventName="Click"></asp:AsyncPostBackTrigger>

                          <asp:AsyncPostBackTrigger ControlID="lnkB" EventName="Click"></asp:AsyncPostBackTrigger>

                          <asp:AsyncPostBackTrigger ControlID="lnkC" EventName="Click"></asp:AsyncPostBackTrigger>

                          <asp:AsyncPostBackTrigger ControlID="lnkD" EventName="Click"></asp:AsyncPostBackTrigger>

                          <asp:AsyncPostBackTrigger ControlID="lnkE" EventName="Click"></asp:AsyncPostBackTrigger>

                          <asp:AsyncPostBackTrigger ControlID="lnkF" EventName="Click"></asp:AsyncPostBackTrigger>

                          <asp:AsyncPostBackTrigger ControlID="lnkG" EventName="Click"></asp:AsyncPostBackTrigger>

                          <asp:AsyncPostBackTrigger ControlID="lnkH" EventName="Click"></asp:AsyncPostBackTrigger>

                          <asp:AsyncPostBackTrigger ControlID="lnkI" EventName="Click"></asp:AsyncPostBackTrigger>

                          <asp:AsyncPostBackTrigger ControlID="lnkJ" EventName="Click"></asp:AsyncPostBackTrigger>

                          <asp:AsyncPostBackTrigger ControlID="lnkK" EventName="Click"></asp:AsyncPostBackTrigger>

                          <asp:AsyncPostBackTrigger ControlID="lnkL" EventName="Click"></asp:AsyncPostBackTrigger>

                          <asp:AsyncPostBackTrigger ControlID="lnkM" EventName="Click"></asp:AsyncPostBackTrigger>

                          <asp:AsyncPostBackTrigger ControlID="lnkN" EventName="Click"></asp:AsyncPostBackTrigger>

                          <asp:AsyncPostBackTrigger ControlID="lnkO" EventName="Click"></asp:AsyncPostBackTrigger>

                          <asp:AsyncPostBackTrigger ControlID="lnkP" EventName="Click"></asp:AsyncPostBackTrigger>

                          <asp:AsyncPostBackTrigger ControlID="lnkQ" EventName="Click"></asp:AsyncPostBackTrigger>

                          <asp:AsyncPostBackTrigger ControlID="lnkR" EventName="Click"></asp:AsyncPostBackTrigger>

                          <asp:AsyncPostBackTrigger ControlID="lnkS" EventName="Click"></asp:AsyncPostBackTrigger>

                          <asp:AsyncPostBackTrigger ControlID="lnkT" EventName="Click"></asp:AsyncPostBackTrigger>

                          <asp:AsyncPostBackTrigger ControlID="lnkU" EventName="Click"></asp:AsyncPostBackTrigger>

                          <asp:AsyncPostBackTrigger ControlID="lnkV" EventName="Click"></asp:AsyncPostBackTrigger>

                          <asp:AsyncPostBackTrigger ControlID="lnkW" EventName="Click"></asp:AsyncPostBackTrigger>

                          <asp:AsyncPostBackTrigger ControlID="lnkX" EventName="Click"></asp:AsyncPostBackTrigger>

                          <asp:AsyncPostBackTrigger ControlID="lnkY" EventName="Click"></asp:AsyncPostBackTrigger>

                          <asp:AsyncPostBackTrigger ControlID="lnkZ" EventName="Click"></asp:AsyncPostBackTrigger>

                          <asp:AsyncPostBackTrigger ControlID="lnkALL" EventName="Click"></asp:AsyncPostBackTrigger>

                          <asp:PostBackTrigger ControlID="btnExportGrid" /> 

                      </Triggers>

                                </Triggers>

                    </asp:UpdatePanel>

                    </td>

                </tr>
 
 
 

    Protected Sub BtnExportGrid_Click(ByVal sender As Object, ByVal args As EventArgs)

        GridViewExportUtil.Export("ProdList.xls", Me.gvProd)

    End Sub
 

 
 
 

Imports System

Imports System.Data

Imports System.Configuration

Imports System.IO

Imports System.Web

Imports System.Web.Security

Imports System.Web.UI

Imports System.Web.UI.WebControls

Imports System.Web.UI.WebControls.WebParts

Imports System.Web.UI.HtmlControls
 
 

Public Class GridViewExportUtil
 

    Public Shared Sub Export(ByVal fileName As String, ByVal gv As GridView)

        HttpContext.Current.Response.Clear()

        HttpContext.Current.Response.AddHeader("content-disposition", String.Format("attachment; filename={0}", fileName))

        HttpContext.Current.Response.ContentType = "application/ms-excel"

        Dim sw As StringWriter = New StringWriter

        Dim htw As HtmlTextWriter = New HtmlTextWriter(sw)

        '  Create a form to contain the grid

        Dim table As Table = New Table

        table.GridLines = gv.GridLines

        '  add the header row to the table

        If (Not (gv.HeaderRow) Is Nothing) Then

            GridViewExportUtil.PrepareControlForExport(gv.HeaderRow)

            table.Rows.Add(gv.HeaderRow)

        End If

        '  add each of the data rows to the table

        For Each row As GridViewRow In gv.Rows

            GridViewExportUtil.PrepareControlForExport(row)

            table.Rows.Add(row)

        Next

        '  add the footer row to the table

        If (Not (gv.FooterRow) Is Nothing) Then

            GridViewExportUtil.PrepareControlForExport(gv.FooterRow)

            table.Rows.Add(gv.FooterRow)

        End If

        '  render the table into the htmlwriter

        table.RenderControl(htw)

        '  render the htmlwriter into the response

        HttpContext.Current.Response.Write(sw.ToString)

        HttpContext.Current.Response.End()

    End Sub
 

    ' Replace any of the contained controls with literals

    Private Shared Sub PrepareControlForExport(ByVal control As Control)

        Dim i As Integer = 0

        Do While (i < control.Controls.Count)

            Dim current As Control = control.Controls(i)

            If (TypeOf current Is LinkButton) Then

                control.Controls.Remove(current)

                control.Controls.AddAt(i, New LiteralControl(CType(current, LinkButton).Text))

            ElseIf (TypeOf current Is ImageButton) Then

                control.Controls.Remove(current)

                control.Controls.AddAt(i, New LiteralControl(CType(current, ImageButton).AlternateText))

            ElseIf (TypeOf current Is HyperLink) Then

                control.Controls.Remove(current)

                control.Controls.AddAt(i, New LiteralControl(CType(current, HyperLink).Text))

            ElseIf (TypeOf current Is DropDownList) Then

                control.Controls.Remove(current)

                control.Controls.AddAt(i, New LiteralControl(CType(current, DropDownList).SelectedItem.Text))

            ElseIf (TypeOf current Is CheckBox) Then

                control.Controls.Remove(current)

                control.Controls.AddAt(i, New LiteralControl(CType(current, CheckBox).Checked))

                'TODO: Warning!!!, inline IF is not supported ?

            End If

            If current.HasControls Then

                GridViewExportUtil.PrepareControlForExport(current)

            End If

            i = (i + 1)

        Loop

    End Sub

End Class

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Comment
Question by:synapse88
4 Comments
 
LVL 15

Accepted Solution

by:
jinal earned 500 total points
ID: 24843672
Hello ,

As you are usingi nside update panel.

Try to rebind grid inside export . It may solve your problem .

It may in this function

Protected Sub BtnExportGrid_Click(ByVal sender As Object, ByVal args As EventArgs)
// Write bind code over here.
        GridViewExportUtil.Export("ProdList.xls", Me.gvProd)
    End Sub

0
 

Author Comment

by:synapse88
ID: 25063123
Hi learnedone, sorry i forgot about this thread.

i'll try the recommended solution and post back the results.

thanks
0

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