Problem

The getTable().addRow() workflow fails when working with tables loaded from Excel files, throwing:

Cannot read properties of undefined (reading 'length')

This prevents a common use case: loading an Excel template with existing tables and adding rows to them programmatically.

Additionally, even when the error doesn't occur:

• Table references don't expand dynamically when rows are added
• Excel filter buttons disappear after save/load cycle
• Missing worksheet references cause inconsistent behavior

Solution

This PR fixes the table loading and addRow workflow with comprehensive changes to lib/doc/table.js and lib/doc/worksheet.js.

Key Changes

lib/doc/table.js:

• Fixed autoFilterRef to target header row only (e.g., A1:C1) instead of all filter rows
• Added _updateTableRef() method to dynamically update table ranges when rows change
• Modified addRow() to update table references and call commit() to re-render properly
• Modified removeRows() to update table references after removal
• Added _writeRowToWorksheet() helper for targeted row writes
• Added autoFilterRef getter/setter

lib/doc/worksheet.js:

• Map tableRef to ref for Excel format compatibility when loading
• Add empty rows array for loaded tables (Excel doesn't store row data in definitions)
• Auto-detect headerRow when columns have names
• Enable filterButton: true on columns when autoFilterRef exists

test/test-table-addrow.js:

• Comprehensive test suite for the getTable().addRow() workflow
• Tests both creating new tables and loading existing tables
• Verifies table references update correctly
• Verifies filter buttons are preserved

Example Usage

// Common template-based workflow - now works!
const Excel = require('exceljs');
const workbook = new Excel.Workbook();
await workbook.xlsx.readFile('template.xlsx');

const worksheet = workbook.getWorksheet('Data');
const table = worksheet.getTable('MyTable');

// Add rows to the loaded table
table.addRow(['Alice', 30, 'alice@example.com']);
table.addRow(['Bob', 25, 'bob@example.com']);

// Save with updated table
await workbook.xlsx.writeFile('output.xlsx');
// Filter buttons preserved ✅
// Table reference expanded correctly ✅

Test Results

$ node test/test-table-addrow.js /tmp/test.xlsx
Initial table created with 3 rows
Table retrieved: MyTable
Initial table ref: A1
Initial table rows: 3
Initial autoFilterRef: A1:C1

Adding new row with addRow()...
After addRow:
Table ref: A1:C5          # ✅ Expanded correctly
Table rows: 4
AutoFilterRef: A1:C1      # ✅ Header row only

=== Test 2: Load and modify table ===
Workbook loaded successfully
Loaded table: LoadTestTable
Adding row to loaded table...
After addRow to loaded table:
Table ref: B2:D3          # ✅ Expanded correctly
AutoFilterRef: B2:D2      # ✅ Preserved

SUCCESS: All table addRow tests passed!

Credits

Original implementation by Ryan Martin (@rmartin93)

• Source: https://github.com/rmartin93/exceljs-fork (commit 6b77cea)
• Discussion: ExcelJS Community Fork - Fixing Critical Bugs & Looking for Maintainers #2987

This PR adopts and submits Ryan's excellent work to upstream with comprehensive testing.

Related Issues

• ExcelJS Community Fork - Fixing Critical Bugs & Looking for Maintainers #2987 - Discussion about table functionality issues
• Fixes the core issue preventing template-based Excel workflows

Checklist

• Code changes implement the fix
• Comprehensive test coverage added
• Tests pass locally
• Existing tests still pass
• Original author credited

Impact

This fix enables:

• ✅ Template-based Excel workflows (load + modify + save)
• ✅ Dynamic table population from databases
• ✅ Preserving Excel table features (filters, formatting)
• ✅ Professional data reporting pipelines

This is a critical fix for enterprise/production use cases where Excel templates are common.