reading Excel Open XML is ignoring blank cells

Question

I am using the accepted solution here to convert an excel sheet into a datatable. This works fine if I have \"perfect\" data but if I have a blank cell in the middle of my

Answer 1

With apologies for posting yet another answer to this question, here's the code I used.

I was having problems with OpenXML not working properly if a worksheet had a blank row at the top. It would sometimes just return a DataTable with 0 rows and 0 columns in it. The code below copes with this, and all other worksheets.

Here's how you would call my code. Just pass in a filename and the name of the Worksheet to read in:

DataTable dt = OpenXMLHelper.ExcelWorksheetToDataTable("C:\\SQL Server\\SomeExcelFile.xlsx", "Mikes Worksheet");

And here's the code itself:

    public class OpenXMLHelper
    {
        //  A helper function to open an Excel file using OpenXML, and return a DataTable containing all the data from one
        //  of the worksheets.
        //
        //  We've had lots of problems reading in Excel data using OLEDB (eg the ACE drivers no longer being present on new servers,
        //  OLEDB not working due to security issues, and blatantly ignoring blank rows at the top of worksheets), so this is a more 
        //  stable method of reading in the data.
        //
        public static DataTable ExcelWorksheetToDataTable(string pathFilename, string worksheetName)
        {
            DataTable dt = new DataTable(worksheetName);

            using (SpreadsheetDocument document = SpreadsheetDocument.Open(pathFilename, false))
            {
                // Find the sheet with the supplied name, and then use that 
                // Sheet object to retrieve a reference to the first worksheet.
                Sheet theSheet = document.WorkbookPart.Workbook.Descendants().Where(s => s.Name == worksheetName).FirstOrDefault();
                if (theSheet == null)
                    throw new Exception("Couldn't find the worksheet: " + worksheetName);

                // Retrieve a reference to the worksheet part.
                WorksheetPart wsPart = (WorksheetPart)(document.WorkbookPart.GetPartById(theSheet.Id));
                Worksheet workSheet = wsPart.Worksheet;

                string dimensions = workSheet.SheetDimension.Reference.InnerText;       //  Get the dimensions of this worksheet, eg "B2:F4"

                int numOfColumns = 0;
                int numOfRows = 0;
                CalculateDataTableSize(dimensions, ref numOfColumns, ref numOfRows);
                System.Diagnostics.Trace.WriteLine(string.Format("The worksheet \"{0}\" has dimensions \"{1}\", so we need a DataTable of size {2}x{3}.", worksheetName, dimensions, numOfColumns, numOfRows));

                SheetData sheetData = workSheet.GetFirstChild();
                IEnumerable rows = sheetData.Descendants();

                string[,] cellValues = new string[numOfColumns, numOfRows];

                int colInx = 0;
                int rowInx = 0;
                string value = "";
                SharedStringTablePart stringTablePart = document.WorkbookPart.SharedStringTablePart;

                //  Iterate through each row of OpenXML data, and store each cell's value in the appropriate slot in our [,] string array.
                foreach (Row row in rows)
                {
                    for (int i = 0; i < row.Descendants().Count(); i++)
                    {
                        //  *DON'T* assume there's going to be one XML element for each column in each row...
                        Cell cell = row.Descendants().ElementAt(i);
                        if (cell.CellValue == null || cell.CellReference == null)
                            continue;                       //  eg when an Excel cell contains a blank string

                        //  Convert this Excel cell's CellAddress into a 0-based offset into our array (eg "G13" -> [6, 12])
                        colInx = GetColumnIndexByName(cell.CellReference);             //  eg "C" -> 2  (0-based)
                        rowInx = GetRowIndexFromCellAddress(cell.CellReference)-1;     //  Needs to be 0-based

                        //  Fetch the value in this cell
                        value = cell.CellValue.InnerXml;
                        if (cell.DataType != null && cell.DataType.Value == CellValues.SharedString)
                        {
                            value = stringTablePart.SharedStringTable.ChildElements[Int32.Parse(value)].InnerText;
                        }

                        cellValues[colInx, rowInx] = value;
                    }
                }

                //  Copy the array of strings into a DataTable.
                //  We don't (currently) make any attempt to work out which columns should be numeric, rather than string.
                for (int col = 0; col < numOfColumns; col++)
                    dt.Columns.Add("Column_" + col.ToString());

                for (int row = 0; row < numOfRows; row++)
                {
                    DataRow dataRow = dt.NewRow();
                    for (int col = 0; col < numOfColumns; col++)
                    {
                        dataRow.SetField(col, cellValues[col, row]);
                    }
                    dt.Rows.Add(dataRow);
                }

#if DEBUG
                //  Write out the contents of our DataTable to the Output window (for debugging)
                string str = "";
                for (rowInx = 0; rowInx < maxNumOfRows; rowInx++)
                {
                    for (colInx = 0; colInx < maxNumOfColumns; colInx++)
                    {
                        object val = dt.Rows[rowInx].ItemArray[colInx];
                        str += (val == null) ? "" : val.ToString();
                        str += "\t";
                    }
                    str += "\n";
                }
                System.Diagnostics.Trace.WriteLine(str);
#endif
                return dt;
            }
        }

        private static void CalculateDataTableSize(string dimensions, ref int numOfColumns, ref int numOfRows)
        {
            //  How many columns & rows of data does this Worksheet contain ?  
            //  We'll read in the Dimensions string from the Excel file, and calculate the size based on that.
            //      eg "B1:F4" -> we'll need 6 columns and 4 rows.
            //
            //  (We deliberately ignore the top-left cell address, and just use the bottom-right cell address.)
            try
            {
                string[] parts = dimensions.Split(':');     // eg "B1:F4" 
                if (parts.Length != 2)
                    throw new Exception("Couldn't find exactly *two* CellAddresses in the dimension");

                numOfColumns = 1 + GetColumnIndexByName(parts[1]);     //  A=1, B=2, C=3  (1-based value), so F4 would return 6 columns
                numOfRows = GetRowIndexFromCellAddress(parts[1]);
            }
            catch
            {
                throw new Exception("Could not calculate maximum DataTable size from the worksheet dimension: " + dimensions);
            }
        }

        public static int GetRowIndexFromCellAddress(string cellAddress)
        {
            //  Convert an Excel CellReference column into a 1-based row index
            //  eg "D42"  ->  42
            //     "F123" ->  123
            string rowNumber = System.Text.RegularExpressions.Regex.Replace(cellAddress, "[^0-9 _]", "");
            return int.Parse(rowNumber);
        }

        public static int GetColumnIndexByName(string cellAddress)
        {
            //  Convert an Excel CellReference column into a 0-based column index
            //  eg "D42" ->  3
            //     "F123" -> 5
            var columnName = System.Text.RegularExpressions.Regex.Replace(cellAddress, "[^A-Z_]", "");
            int number = 0, pow = 1;
            for (int i = columnName.Length - 1; i >= 0; i--)
            {
                number += (columnName[i] - 'A' + 1) * pow;
                pow *= 26;
            }
            return number - 1;
        }
    }