How to download a dynamically generated file without blocking the page ?

Question

In one of my webpart I have a feature to generate a file dynamically depending on what the users choosed in the view.

On my OnClick event handler, I have this code :

protected void reportClick(object sender, EventArgs e)
{
    MemoryStream ms = GenerateFile();

    ms.Seek(0, SeekOrigin.Begin);

    byte[] byteArray = ms.ToArray();

    ms.Flush();
    ms.Close();

    Context.Response.Clear();
    Context.Response.AddHeader("Content-Disposition", "attachment; filename=report.docx");
    Context.Response.AddHeader("Content-Length", byteArray.Length.ToString());
    Context.Response.ContentType = "application/octet-stream";
    Context.Response.BinaryWrite(byteArray);
    Context.Response.End();
}

It works as the file is proposed to download to the user. The problem is that after the download, the page is blocked: the buttons are still clickable but there are no actions done on the click. I have to refresh the page to enable the actions again.

Is there a way to download a file without blocking the page ?

Answer 1

In your webpart code you can do this by rendering a hyperlink to a SharePoint application page (under the _layouts folder), rather than a button. The application page should contain the code to dynamically generate your file.