Question

I am wondering if I need to do something(threading etc.) to preclude my file generation failing due to more than one user attempting to run the generation process simultaneously.

If there is a potential problem I want to know any ideas for avoiding it.

Overview of my process.

1. user clicks button to kick off the process.
2. Data is collected from datasource/dummied up for testing.
3. Template.xls is opened
4. data is inserted into opened template.
5. SaveAs is called for the open excel file.
6. process is repeated until all needed files are created.
7. All files zipped together
8. user is informed if process completed successfully and prompted to download the zip of the files.

note: hardcoded filename values are present due to this being a proof of concept at the moment.

See generation code below

private Boolean GenerateExcelFile(int filenum, int totalfiles, int Year)
    {
        String TemplateFilename = "C:\\exceldocs\\Templates\\OSHA300_Template.xls";

        try
        {
            Excel._Application oXL;
            Excel._Workbook oWB;
            Excel._Worksheet oSheet;

            //Start Excel and get Application object.
            oXL = new Excel.Application();
            oXL.Visible = false;

            //Open the workbook template.
            //oWB = (Excel._Workbook)(oXL.Workbooks.Add(Missing.Value));
            oWB = (Excel._Workbook)(oXL.Workbooks.Open(TemplateFilename));
            oSheet = (Excel._Worksheet)oWB.ActiveSheet;

            oSheet.Cells[3, 11] = Year;
            oSheet.Cells[PAGEOFROW, PAGEOFCOL] = filenum + " of " + totalfiles;
            int currentexcelrow = STARTROW;
            foreach (OSHArow row in this)
            {
                FillOutRow(oSheet, row, currentexcelrow++);
                if (currentexcelrow == 38)
                {
                    //break;
                }
            }
            FillOutSummaryRow(oSheet);
            File.Delete("C:\\exceldocs\\OshaOutput\\OSHA300_TestResult" + filenum + ".xls");
            oWB.SaveAs("C:\\exceldocs\\OshaOutput\\OSHA300_TestResult" + filenum + ".xls");
            oWB.Close(true);
        }
        catch (Exception e)
        {
            //TODO: configure an exception log.
            throw e;
            return false;
        }
        return true;
    }

Answer 1

You’re better off using something like the OpenXml library. You can write Excel sheets on the fly to streams (and then return streams as FileResults for the user to download to a XLSX file).

http://openxmldeveloper.org/