How to add a cell comment using NPOI Excel in C#?

Question

I want to create a cell comment iusing NPOI Excel in C#. I have not find any clear document of that. I wrote something by myself as below.

NPOI.HSSF.Record.NoteRecord nr = new NPOI.HSSF.Record.NoteRecord();
nr.Author = "Some Author";
NPOI.HSSF.Record.TextObjectRecord tor = new NPOI.HSSF.Record.TextObjectRecord();
tor.Str = new HSSFRichTextString("something");

HSSFComment cm = new HSSFComment(nr, tor);
cm.Visible = true;

sheet.GetRow(i).Cells[k + 8].CellComment = cm;   

That code is not working correctly. I can not see any comment on that cell in the generated excel file. Is there anybody to know how can I add a comment in the specific cell?

Answer 1

You need to use a drawing patriarch to create a cell comment. Then you can define your author and text. You can also apply some font customization.

Please try this code, I commented the different steps:

HSSFWorkbook workbook = new HSSFWorkbook();
HSSFSheet sheet = (HSSFSheet)workbook.CreateSheet("Sheet1");
HSSFRow row = (HSSFRow)sheet.CreateRow(0);
HSSFCell cell = (HSSFCell)row.CreateCell(0);
cell.SetCellValue("Cell1");

// Create the drawing patriarch (top level container for all shapes including cell comments)
IDrawing patriarch = (HSSFPatriarch)sheet.CreateDrawingPatriarch();

// Client anchor defines size and position of the comment in the worksheet
IComment comment = patriarch.CreateCellComment(new HSSFClientAnchor(0, 0, 0, 0, 2, 1, 4, 4));

// Set comment author
comment.Author = "Author";

// Set text in the comment
comment.String = new HSSFRichTextString($"{comment.Author}:{Environment.NewLine}A comment");

// If you want the author displayed in bold on top like in Excel
// The author will be displayed in the status bar when on mouse over the commented cell
IFont font = workbook.CreateFont();
font.Boldweight = (short)FontBoldWeight.Bold;
comment.String.ApplyFont(0, comment.Author.Length, font);

// Set comment visible
comment.Visible = true;

// Assign comment to a cell
cell.CellComment = comment;

using (MemoryStream exportData = new MemoryStream())
{
    workbook.Write(exportData);
    Response.ContentEncoding = Encoding.UTF8;
    Response.Charset = Encoding.UTF8.EncodingName;
    Response.ContentType = "application/vnd.ms-excel";
    Response.AddHeader("content-disposition", $"attachment; filename=test.xls");
    Response.Clear();
    Response.BinaryWrite(exportData.GetBuffer());
    Response.End();
}

References:

• NPOI HSSF Examples - Cell Comments