Export to CSV on custom application results in that nothing works on the page anymore

Question

i have a simple custom application which fetches records from a lists by a caml query and through an export button the user is able to get a csv file with the data.

Generally the export works fine. But after the export nothign works on the page. I mean it is no longer possible to click on buttons and no events are getting executed (button onclick event).

    private void ExportToCSV(SPListItemCollection items)
    {
        if (items != null && items.Count > 0)
        {
            string attachment = "attachment; filename=export.csv";
            HttpContext.Current.Response.Clear();
            HttpContext.Current.Response.ClearHeaders();
            HttpContext.Current.Response.ClearContent();
            HttpContext.Current.Response.AddHeader("content-disposition", attachment);
            HttpContext.Current.Response.ContentType = "text/csv";

            string columnNames = "Region;Country;Company";
            HttpContext.Current.Response.Write(columnNames);
            HttpContext.Current.Response.Write(Environment.NewLine);

            foreach (SPListItem item in items)
            {
                WriteCompetitorInfoToCSV(item);
                HttpContext.Current.Response.Flush();
            }

            HttpContext.Current.Response.End();
        }
    }

    private void WriteCompetitorInfoToCSV(SPListItem item)
    {
        StringBuilder stringBuilder = new StringBuilder();
        AddSemicolon(new SPFieldLookupValue(item["fielda"] as String).LookupValue, stringBuilder);
        AddSemicolon(new SPFieldLookupValue(item["fieldb"] as String).LookupValue, stringBuilder);
        AddSemicolon(new SPFieldLookupValue(item["fieldc"] as String).LookupValue, stringBuilder);
        HttpContext.Current.Response.Write(stringBuilder.ToString());
        HttpContext.Current.Response.Write(Environment.NewLine);
    }

Why does this happen?

Answer 1

I had this same issue some days ago. Following code works for me to escape this problem.

    protected void Page_Load(object sender, EventArgs e) {
     string js = @"_spSuppressFormOnSubmitWrapper = true;";
     this.Page.ClientScript.RegisterStartupScript(this.GetType(), "js", js, true);
 }