How do I download the PDF file generated given the file path in a Gridview?

Question

I want to write code to allow user to download a PDF by clicking the "Download" linkbutton in a Gridview when the filepath is given in the Gridview.

Here's my code :

aspx

<asp:GridView ID="Gridview1" runat="server" ShowHeaderWhenEmpty="true" 
                            EmptyDataText="No Records Found" AutoGenerateColumns="False" CellPadding="4" ForeColor="#333333" GridLines="None" AutoGenerateSelectButton="true" Font-Size="Small" Width="95%" onselectedindexchanged="Gridview1_SelectedIndexChanged">
    <AlternatingRowStyle BackColor="White" />

    <Columns>
        <asp:BoundField HeaderText="ID" DataField="id" DataFormatString="BSc/{0}" />
        <asp:BoundField HeaderText="Company Name" DataField="ComName" />
        <asp:BoundField HeaderText="Country Incorperated" DataField="Country" />
        <asp:BoundField HeaderText="Date Created" DataField="Date" />
        <asp:BoundField HeaderText="Path" DataField="Path"  />

        <asp:TemplateField>
            <ItemTemplate>
                <asp:LinkButton ID="lnkDownload" Text = "Download" CommandArgument = '<%# Eval("Path") %>' runat="server" OnClick = "DownloadFile"></asp:LinkButton>
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>

    <EditRowStyle BackColor="#2461BF" />
    <FooterStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" />
    <HeaderStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" />
    <PagerStyle BackColor="#2461BF" ForeColor="White" HorizontalAlign="Center" />
    <RowStyle BackColor="#EFF3FB" />
    <SelectedRowStyle BackColor="#D1DDF1" Font-Bold="True" ForeColor="#333333" />
    <SortedAscendingCellStyle BackColor="#F5F7FB" />
    <SortedAscendingHeaderStyle BackColor="#6D95E1" />
    <SortedDescendingCellStyle BackColor="#E9EBEF" />
    <SortedDescendingHeaderStyle BackColor="#4870BE" />
</asp:GridView>

aspx.cs

protected void DownloadFile(object sender, EventArgs e)
{
    string filePath = (sender as LinkButton).CommandArgument;
    Response.ContentType = ContentType;
    Response.AppendHeader("Content-Disposition", "attachment; filename=" + Path.GetFileName(filePath));
    Response.WriteFile(filePath);
    Response.End();
}

I looked up the download code from this site : http://www.aspsnippets.com/Articles/Download-Files-from-GridView-using-LinkButton-Click-Event-in-ASPNet-using-C-and-VBNet.aspx

I also get the file path like I'm supposed to, but thereafter nothing happens. There is no error either.

Please help. Thanks in advance.

Answer 1

Response.WriteFile is an old method that was used in ASP.NET 1.1. Try this code for download instead.

// Clear the content of the response
Response.ClearContent();

// Add the file name and attachment, which will force the open/cance/save dialog to show, to the header
Response.AppendHeader("Content-Disposition", "attachment; filename=" + Path.GetFileName(filePath));

// Add the file size into the response header
Response.AddHeader("Content-Length", filePath.Length.ToString());

// Set the ContentType
Response.ContentType = "application/pdf";

// Write the file into the response (TransmitFile is for ASP.NET 2.0 and above. In ASP.NET 1.1 you have to use WriteFile instead)
Response.TransmitFile(filePath);

Response.Flush();
// End the response
Response.End();

Also, having the grid within an update panel may cause problems when trying to download from a control within the grid itself, because download requires full post back. In this case, consider using PostBackTrigger.