Question

I am trying to create an Excel document using OpenXML (SAX method). When my method is called I want to check to see if a tab has already been created for a given key. If it is I would like to just append a row to the bottom of that tab. If the tab hasn’t been created for a given key I create a new tab like;

      part = wbPart.AddNewPart<WorksheetPart>();

                        string worksheetName = row.Key[i].ToString();

                        Sheet sheet = new Sheet() { Id = document.WorkbookPart.GetIdOfPart(part), SheetId = sheetNumber, Name = worksheetName };
                        sheets.Append(sheet);

                        writer = OpenXmlWriter.Create(part);
                        writer.WriteStartElement(new Worksheet());
                        writer.WriteStartElement(new SheetData());

                        currentrow = 1;

                        string header = Header + "\t" + wrapper.GetHeaderString(3, 2, -1); //need to fix
                        WriteDataToExcel(header, currentrow, 0, writer);
                        currentrow++;


                        writer.WriteEndElement();
                        writer.WriteEndElement();
                        writer.Close();

If the a tab as already been created I recall sheet using the following code;

private static WorksheetPart GetWorksheetPartByName(SpreadsheetDocument document, string sheetName)
    {
        IEnumerable<Sheet> sheets =
           document.WorkbookPart.Workbook.GetFirstChild<Sheets>().
           Elements<Sheet>().Where(s => s.Name == sheetName);

        if (sheets.Count() == 0)
        {
            // The specified worksheet does not exist.

            return null;
        }

        string relationshipId = sheets.First().Id.Value;
        WorksheetPart worksheetPart = (WorksheetPart)
             document.WorkbookPart.GetPartById(relationshipId);
        return worksheetPart;

    }

When the correct Worksheet part is returned I try and add the new row by pointing my OpenXmlWriter to the correct part then adding the row;

   part = GetWorksheetPartByName(document, row.Key[i].ToString());

                        writer = OpenXmlWriter.Create(part);
                        writer.WriteStartElement(part.Worksheet);
                        writer.WriteStartElement(part.Worksheet.GetFirstChild<SheetData>());
                        SheetData sheetData = part.Worksheet.GetFirstChild<SheetData>();
                        Row lastRow = sheetData.Elements<Row>().LastOrDefault();

The code runs however I always end up with just one row (the initial one I added when first creating the tab). No subsequent rows show up in the spreadsheet.

I will be adding a lot of rows (50,000+) and would prefer not to have to create a new file and copy the information over each time.

Answer 1

From my experience, using the SAX method to write (ie, with OpenXmlWriter) works best for new things (parts, worksheets, whatnot). When you use OpenXmlWriter.Create(), that’s like overwriting the original existing data for the part (WorksheetPart in this case). Even though in effect, it’s not. It’s complicated.

As far as my experiments went, if there’s existing data, you can’t edit data using OpenXmlWriter. Not even if you use the Save() function or close the OpenXmlWriter correctly. For some reason, the SDK will ignore your efforts. Hence the original one row that you added.

If you’re writing 50,000 rows, it’s best to do so all at one go. Then the SAX method will be useful. Besides, if you’re writing one row (at a time?), the speed benefits of using SAX versus the DOM method is negligible.