file download functionality

[mww]

Im trying to implement a file download function in a grid.  The grid is controlled by an ajax manager.  In the grid i have a GridButtonColumn

<telerik:GridButtonColumn ButtonType="ImageButton"
                                        CommandName="ImageDownload" Text="Download" UniqueName="ImageDownload" ImageUrl="~/images/dnn.gif">
                                        <HeaderStyle Width="20px" />
                                        <ItemStyle HorizontalAlign="Center" />
                                    </telerik:GridButtonColumn>

I then have this function that should initiate the file save dialog for users to save the selected file to their file system

protected void RadGridImages_ItemCommand(object source, GridCommandEventArgs e)

        {

                         

            if (e.CommandName.Equals("ImageDownload"))

            {
//commandargument has the physical path on the server of the selected file

                DownloadImage(e.CommandArgument.ToString());

            }

        }

 

        private void DownloadImage(string imagePath)

        {

            FileInfo file = new FileInfo(imagePath);

            if (file.Exists)

            {

                Response.ClearContent();

                Response.AddHeader("Content-Disposition", "attachment; filename=" + file.Name);

                Response.AddHeader("Content-Length", file.Length.ToString());

                Response.ContentType = Studio1BusinessLayer.Helpers.ReturnExtension(file.Extension.ToLower());

                Response.TransmitFile(file.FullName);

                Response.End();

            }

        }

The DownloadImage method generates this error

Could not complete the operation due to error c00ce514.

Can anyone show me how to achieve a simple file download function in a radgrid ?

[Radoslav]

Hello Mww,

Could you please try disabling the ajax when the Download button is pressed. Due to the limitations of the javascript XmlHttpRequest object used for AJAX, to download or upload attachments, AJAX needs to be temporarily disabled, so that the page performs a full postback.  On the following online example you could see how to disable AJAX:
http://demos.telerik.com/aspnet-ajax/grid/examples/generalfeatures/gridattachmentcolumn/defaultcs.aspx

I hope this helps.

Best wishes,
Radoslav
the Telerik team

[RvdGrint]

Radoslav,

I've the same problem with a GridAttachmentColumn. I've 'copied' the example you mentioned but still keep the c00ce514 error.

[Radoslav]

Hello Jos,

I tried to reproduce the described issue, but to no avail. I am sending you a simple example, based on the mentioned demo. Please check it out and let me know what differs in your case.

Looking forward for your reply.

Kind regards,
Radoslav
the Telerik team

[Jhess]

I have this problem for downloading pdf file.. see below details.

MTR_ShipersCode = char
error: Specified cast is not valid.
int attachmentId = (int)args.AttachmentKeyValues["MTR_ShipersCode"]

Hope you can help me with this.

Thank you,
Jhess

[Radoslav]

Hi Jhess,

Based on the provided information is hard to say what is caused the described issue. Could you please post your aspx markup code with the related code behind or send us a sample where we could replicate the issue.  Thus we will be able to gather more details about your scenario and to provide you a solution.

Looking forward for your reply.

Regards,
Radoslav
the Telerik team

[M]

This example works great,
but my issue is that my files are located on the web server in a folder called 'files' (not in a table).
How do I make that work?

Thanks,
Mike

[Radoslav]

Hello Mike,

When the files are located on the file system you could not use GridAttachmentColumn. In this case you could try adding a GridTemplateColumn with the asp:LinkButton (with set CommandName) into its ItemTemplate. Then when the LinkButton is clicked you could handle the RadGrid ItemCommand event, find pointed file into the file system and send it with the response. More information about how to download file you could find here:
http://www.daniweb.com/web-development/aspnet/threads/252778/file-download-in-asp.net-using-c-code
http://www.venkateswarlu.co.in/articles/DotNet/Download_File.aspx
http://codes.codedigest.com/CodeDigest/39-File-Download-in-ASP-Net-with-C-.aspx

I hope this helps.

All the best,
Radoslav
the Telerik team