导出到Excel错误

Question

I am attempting to export a datagrid to excel via a popup. I am able to successfully export to excel when removing the code from my application, however, when attempting to export to excel using the exact same code within my application, I receive the following errors:

From my try/catch:

Unable to evaluate expression because the code is optimized or a native frame is on top of the call stack.

...and from the console:

Error: Sys.WebForms.PageRequestManagerParserErrorException: The message received from the server could not be parsed.

My server-side code is as follows:

protected void btnExportToExcel_Click(object sender, EventArgs e)
    {
        ExportDataSetToExcel();
    }

private void ExportDataSetToExcel()
    {

        try
        {
            DataTable dt = new DataTable("GridView_Data");
            foreach (TableCell cell in gvPatientRoster.HeaderRow.Cells)
            {
                dt.Columns.Add(cell.Text);
            }
            foreach (GridViewRow row in gvPatientRoster.Rows)
            {
                dt.Rows.Add();
                for (int i = 0; i < row.Cells.Count; i++)
                {
                    dt.Rows[dt.Rows.Count - 1][i] = row.Cells[i].Text;
                }
            }
            if (dt != null && dt.Rows.Count > 0)
            {
                Response.ContentType = "application/vnd.ms-excel";
                Response.AppendHeader("Content-Disposition",
                    string.Format("attachment; filename=PatientRoster.xls"));

                System.IO.StringWriter tw = new System.IO.StringWriter();
                System.Web.UI.HtmlTextWriter hw =
                    new System.Web.UI.HtmlTextWriter(tw);
                DataGrid dgGrid = new DataGrid();
                dgGrid.DataSource = dt;

                //Report Header
                hw.WriteLine("<b><u><font size='5'>" +
                             "Patient Roster</font></u></b>");
                hw.WriteLine("<br><br>");
                //hw.Write(BuildCriteriaString());
                hw.WriteLine("<br>");
                // Get the HTML for the control.
                dgGrid.HeaderStyle.Font.Bold = true;
                dgGrid.DataBind();
                dgGrid.RenderControl(hw);

                // Write the HTML back to the browser.

                this.EnableViewState = false;
                Response.Write(tw.ToString());
                Response.End();
            }
        }
        catch (Exception ex)
        {
            lblErrorMessage.Text = ex.Message;
        }

    }

Answer 1

I added the following to the PageLoad() and the export now works:

ScriptManager scriptManager = ScriptManager.GetCurrent(this.Page);
scriptManager.RegisterPostBackControl(this.btnExportToExcel);

It looks like the UpdatePanel and ScriptManager were elements that I overlooked. When I separated the functionality from the main application, I did not include all HTML that was in the main application. Since the ScriptManager and UpdatePanel were not part of the isolated functionality, it worked properly. I will be sure to post the HTML next time

This was a solution from the following post:

Sys.WebForms.PageRequestManagerParserErrorException: The message received from the server could not be parsed

Answer 2

I would suggest using one of the many good, free C# "Export to Excel" libraries out there.

You've already written the code to read your DataView into a DataTable , and once it's in this format, using the following free C# library...

ExportToExcel library

...you'd be able to export the data into a "real" Excel 2007 file in one line of code....

//  Export the DataTable into an Excel file, and write it to the web Response
CreateExcelFile.CreateExcelDocument(dt, "SomeFilename.xlsx", Response);

Okay, okay, two lines of code. I added a comment.

But you get the point !