Macros (xlsm)

dotnet-poi preserves VBA macros when round-tripping xlsm files. The vbaProject.bin is kept byte-for-byte.

Preserving Macros on Round-Trip

using var stream = File.OpenRead("macro-workbook.xlsm");
using var wb = new XSSFWorkbook(stream);

// Make changes to cells, styles, etc.
var sheet = wb.getSheetAt(0);
var row = sheet.getRow(0) ?? sheet.createRow(0);
row.createCell(5).setCellValue("New data");

// Save — macro bytes are preserved automatically
using var outStream = File.Create("macro-workbook-modified.xlsm");
wb.write(outStream);

No special handling is needed. The macro parts are automatically preserved as long as you don't remove them.

Creating Macro-Enabled Files

To create a new xlsm file, write using the xlsm extension. The workbook type is determined by the content:

using var wb = new XSSFWorkbook();
// ... add content ...
using var file = File.Create("output.xlsm");
wb.write(file);

For template-based workflows, start from an existing xlsm that contains the macros you need.

Limitations

• Creating new VBA macros programmatically is not supported
• Reading VBA project contents is not supported
• Editing VBA macro source code is not supported
• Adding or removing macro references is not supported

Verified Formats

Full Runnable Example

See examples/UsageSamples/Program.cs (CreateMacroWorkbookRoundTrip):

examples/UsageSamples