C#, Write XLSX using OpenXmlWriter and Open XML SDK

Question

In C#, the following program compiles and runs, but it doesn't write anything in the excel output file.

I got it working without the OpenXmlWriter but I started running out of memory so I have to switch to the OpenXmlWriter according to this http://blogs.msdn.com/b/brian_jones/archive/2010/06/22/writing-large-excel-files-with-the-open-xml-sdk.aspx

class Program
{
    static void Main(string[] args)
    {
        File.Copy("book.xlsx", "output.xlsx", true);
        WriteValuesSAX("output.xlsx", 10, 10);
    }

    static void WriteValuesSAX(string filename, int numRows, int numCols)
    {
        using (SpreadsheetDocument myDoc = 
               SpreadsheetDocument.Open(filename, true))
        {
            WorkbookPart workbookPart = myDoc.WorkbookPart;
            WorksheetPart worksheetPart = workbookPart.WorksheetParts.First();

            OpenXmlWriter writer = OpenXmlWriter.Create(worksheetPart);

            Row r = new Row();
            Cell c = new Cell();
            CellValue v = new CellValue("Test");
            c.AppendChild(v);

            writer.WriteStartElement(new SheetData());
            for (int row = 0; row < numRows; row++)
            {
                writer.WriteStartElement(r);
                for (int col = 0; col < numCols; col++)
                {
                    writer.WriteElement(c);
                }
                writer.WriteEndElement();
            }
            writer.WriteEndElement();

            writer.Close();
        }
    }
}

Why doesn't it write anything to output?

Solution 1

I don't understand this well enough yet, but I got it working. Here's what I ended up with.

class Program
{
    static void Main(string[] args)
    {
        File.Copy("book.xlsx", "output.xlsx", true);
        WriteRandomValuesSAX("output.xlsx", 10, 10);
    }

    static void WriteRandomValuesSAX(string filename, int numRows, int numCols)
    {
        using (SpreadsheetDocument myDoc = SpreadsheetDocument.Open(filename, true))
        {
            WorkbookPart workbookPart = myDoc.WorkbookPart;
            WorksheetPart worksheetPart = workbookPart.WorksheetParts.Last();

            OpenXmlWriter writer = OpenXmlWriter.Create(worksheetPart);

            Row r = new Row();
            Cell c = new Cell();
            CellValue v = new CellValue("Test");
            c.AppendChild(v);

            writer.WriteStartElement(new Worksheet());
            writer.WriteStartElement(new SheetData());
            for (int row = 0; row < numRows; row++)
            {
                writer.WriteStartElement(r);
                for (int col = 0; col < numCols; col++)
                {
                    writer.WriteElement(c);
                }
                writer.WriteEndElement();
            }
            writer.WriteEndElement();
            writer.WriteEndElement();

            writer.Close();
        }
    }
}

Notice I added writer.WriteStartElement(new Worksheet()); and another writer.WriteEndElement();

---

I found the correct xml format here: http://msdn.microsoft.com/en-us/library/gg278309.aspx

Which is

<?xml version="1.0" encoding="utf-8"?> <x:worksheet xmlns:x="http://schemas.openxmlformats.org/spreadsheetml/2006/main">
    <x:sheetData>
        <x:row r="1">
            <x:c r="A1" t="n">
                <x:v>100</x:v>
            </x:c>
        </x:row>
    </x:sheetData> </x:worksheet>

So I opened (unzipped) the xlsx file and navigated to output.xlsx\xl\worksheets\sheet1.xml and saw that I was missing the <x:worksheet>.

Solution 2

Using the code above gives me the error message "Excel found unreadable content" in Excel 2007. Using information from here how-to-properly-use-openxmlwriter-to-write-large-excel-files and changing the code when adding the columns to the following removed the error.

for(int col = 0; col < numCols; col++)
{
    var oxa = new List<OpenXmlAttribute>();
    oxa.Add(new OpenXmlAttribute("t",null,"str"));
    writer.WriteStartElement(c,oxa);
    writer.WriteElement(new CellValue(string.Format("R{0}C{1}", row, col)));
    writer.WriteEndElement();
}