Open XML SDK 2.0 - how to update a cell in a spreadsheet?

Here is the working code. This is a prototype. For a larger number of changes, one might open the document only once. Also, there are some hard-coded things like sheet name and cell type that would have to be parameterized before this can be called production-ready.http://openxmldeveloper.org/forums/4005/ShowThread.aspx was very helpful.

using System;using System.Collections.Generic;using System.Data;using System.Linq;using System.Text;using DocumentFormat.OpenXml;using DocumentFormat.OpenXml.Packaging;using DocumentFormat.OpenXml.Spreadsheet;using System.Xml;using System.IO;using System.Diagnostics;namespace OpenXMLWindowsApp{    public class OpenXMLWindowsApp    {        public void UpdateSheet()        {            UpdateCell("Chart.xlsx", "20", 2, "B");            UpdateCell("Chart.xlsx", "80", 3, "B");            UpdateCell("Chart.xlsx", "80", 2, "C");            UpdateCell("Chart.xlsx", "20", 3, "C");            ProcessStartInfo startInfo = new ProcessStartInfo("Chart.xlsx");            startInfo.WindowStyle = ProcessWindowStyle.Normal;            Process.Start(startInfo);        }        public static void UpdateCell(string docName, string text,            uint rowIndex, string columnName)        {            // Open the document for editing.            using (SpreadsheetDocument spreadSheet =                      SpreadsheetDocument.Open(docName, true))            {                WorksheetPart worksheetPart =                       GetWorksheetPartByName(spreadSheet, "Sheet1");                if (worksheetPart != null)                {                    Cell cell = GetCell(worksheetPart.Worksheet,                                              columnName, rowIndex);                    cell.CellValue = new CellValue(text);                    cell.DataType =                         new EnumValue<CellValues>(CellValues.Number);                    // Save the worksheet.                    worksheetPart.Worksheet.Save();                }            }        }        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;        }        // Given a worksheet, a column name, and a row index,         // gets the cell at the specified column and         private static Cell GetCell(Worksheet worksheet,                   string columnName, uint rowIndex)        {            Row row = GetRow(worksheet, rowIndex);            if (row == null)                return null;            return row.Elements<Cell>().Where(c => string.Compare                   (c.CellReference.Value, columnName +                    rowIndex, true) == 0).First();        }        // Given a worksheet and a row index, return the row.        private static Row GetRow(Worksheet worksheet, uint rowIndex)        {            return worksheet.GetFirstChild<SheetData>().              Elements<Row>().Where(r => r.RowIndex == rowIndex).First();        }     }}

I've been working with excel and found this helper library to be of great help (I've created my own helpers for word, would have saved at least 2 weeks if I was aware of this):https://www.nuget.org/packages/SimpleOOXML/

This is what is needed to update cell (writer.PasteText(...)):

MemoryStream stream = SpreadsheetReader.Create();SpreadsheetDocument doc = SpreadsheetDocument.Open(stream, true);WorksheetPart worksheetPart = SpreadsheetReader.GetWorksheetPartByName(doc, "Sheet1");WorksheetWriter writer = new WorksheetWriter(doc, worksheetPart);writer.PasteText("B2", "Hello World");//Save to the memory streamSpreadsheetWriter.Save(doc);byte[] result = stream.ToArray();FileStream file = new FileStream(@"D:\x1.xlsx", FileMode.Create);file.Write(result, 0, result.Length);file.Close();

The Code posted by @CDonner throws some exceptions, i have added some of the code that will take care of code, which throws an Exceptions, here it is

using System;using System.Collections.Generic;using System.Data;using System.Linq;using System.Text;using DocumentFormat.OpenXml;using DocumentFormat.OpenXml.Packaging;using DocumentFormat.OpenXml.Spreadsheet;using System.Xml;using System.IO;using System.Diagnostics;namespace Application.Model{public class TempCode{    public TempCode()    {        UpdateCell("E:/Visual Studio Code/Book1.xlsx", "120", 1, "A");        UpdateCell("E:/Visual Studio Code/Book1.xlsx", "220", 2, "B");        UpdateCell("E:/Visual Studio Code/Book1.xlsx", "320", 3, "C");        UpdateCell("E:/Visual Studio Code/Book1.xlsx", "420", 4, "D");        UpdateCell("E:/Visual Studio Code/Book1.xlsx", "520", 5, "E");        ProcessStartInfo startInfo = new ProcessStartInfo("E:/Visual Studio Code/Book1.xlsx");        startInfo.WindowStyle = ProcessWindowStyle.Normal;        Process.Start(startInfo);    }    public static void UpdateCell(string docName, string text,uint rowIndex, string columnName){        // Open the document for editing.        using (SpreadsheetDocument spreadSheet = SpreadsheetDocument.Open(docName, true))        {            WorksheetPart worksheetPart = GetWorksheetPartByName(spreadSheet, "Sheet2");            if (worksheetPart != null)            {                Cell cell = GetCell(worksheetPart.Worksheet, columnName, rowIndex);                cell.CellValue = new CellValue(text);                cell.DataType = new EnumValue<CellValues>(CellValues.Number);                // Save the worksheet.                worksheetPart.Worksheet.Save();            }        }    }    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){            return null;        }        string relationshipId = sheets.First().Id.Value;        WorksheetPart worksheetPart = (WorksheetPart)document.WorkbookPart.GetPartById(relationshipId);        return worksheetPart;    }    private static Cell GetCell(Worksheet worksheet, string columnName, uint rowIndex)    {        Row row;        string cellReference = columnName + rowIndex;        if (worksheet.Elements<Row>().Where(r => r.RowIndex == rowIndex).Count() != 0)            row = worksheet.GetFirstChild<SheetData>().Elements<Row>().Where(r => r.RowIndex == rowIndex).FirstOrDefault();        else{            row = new Row() { RowIndex = rowIndex };            worksheet.Append(row);        }        if (row == null)            return null;        if (row.Elements<Cell>().Where(c => c.CellReference.Value == cellReference).Count() > 0) {            return row.Elements<Cell>().Where(c => c.CellReference.Value == cellReference).First();        }        else{            Cell refCell = null;            foreach (Cell cell in row.Elements<Cell>()){                if (string.Compare(cell.CellReference.Value, cellReference, true) > 0){                    refCell = cell;                    break;                }            }            Cell newCell = new Cell() {                CellReference = cellReference,                 StyleIndex = (UInt32Value)1U            };            row.InsertBefore(newCell, refCell);            worksheet.Save();            return newCell;        }    }}

}