[OUAO-FRANK]

Summary

A completely empty worksheet is rendered as a heading followed by two lines of broken table syntax, because to_html() on a frame with no columns produces a table with no header, and markdownify turns that into |\n| |:

## HasData
| col |
| --- |
| v |

## CompletelyEmpty
|
|  |

The last two lines are not a table — there is no delimiter row — so a renderer emits them as literal text, and any consumer of the Markdown sees a malformed document.

• Both converters now skip a sheet whose frame has no columns (sheets[s].columns.empty), before the heading is written. That is the XLSX path and the byte-identical XLS path, which had the same loop.
• The guard is on columns rather than on rows on purpose: a sheet that has a header row but no data rows already renders a well-formed empty table (## HeaderOnly\n| col |\n| --- |), and that is the behaviour worth keeping. Only the no-columns case is broken.
• Nothing else changes: sheet order, heading text, image rendering, existingClaim-style options and the .xls/.xlsx selection are untouched.

Testing

$ cd packages/markitdown
$ .venv/Scripts/python -m pytest tests/test_xlsx.py -q
29 passed in 2.76s

$ .venv/Scripts/python -m black --check src/markitdown/converters/_xlsx_converter.py tests/test_xlsx.py
2 files would be left unchanged.

Four new cases at the end of tests/test_xlsx.py (no existing case covered a sheet with zero columns):

case	before	after
single completely empty sheet	'## Empty\n|\n| |'	''
header row, no data rows	'## HeaderOnly\n| col |\n| --- |'	unchanged (guard on the fix)
data sheet, then an empty sheet	'...| v |\n\n## Empty\n|\n| |'	'## HasData\n| col |\n| --- |\n| v |'
empty sheet first, then data	heading for the empty sheet	'## HasData\n| col |\n| --- |\n| v |'

Mutation check: with the guard removed, 3 of the 4 cases fail (test_completely_empty_sheet_is_skipped..., test_data_sheet_followed_by_an_empty_sheet, test_empty_sheet_does_not_hide_the_next_sheet), so the regression bites. The header-only case passes both ways by design.

Reproduced end-to-end first with the snippet from the issue (MarkItDown().convert_stream(..., StreamInfo(extension=".xlsx"))) against main at 4cc9fa1, which produced exactly the malformed output quoted above.

Closes #2470

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[Bicheng (Kenneth) (BichengWang)]

Reviewed head 640f843ed3d99495757806eb6bb36bd33190ea08.

[P2] Preserve image-only worksheets before skipping the sheet — packages/markitdown/src/markitdown/converters/_xlsx_converter.py:157-158

columns.empty only describes cell data. A worksheet containing an embedded image and no cell values can still produce content through the supported _image_to_html extension. This continue bypasses images.to_html(...) below, so the hook is never called and the entire sheet silently disappears.

I reproduced this through MarkItDown.convert_stream() using an XLSX created by openpyxl:

import io
from openpyxl import Workbook
from openpyxl.drawing.image import Image as SheetImage
from PIL import Image
from markitdown import MarkItDown, StreamInfo
from markitdown.converters import XlsxConverter

class CaptionedXlsx(XlsxConverter):
    def _image_to_html(self, image_stream, stream_info, **kwargs):
        return "<p>Quarterly revenue chart</p>"

png = io.BytesIO()
Image.new("RGB", (2, 2), "red").save(png, "PNG")
png.seek(0)
wb = Workbook()
wb.active.title = "ChartOnly"
wb.active.add_image(SheetImage(png), "A1")
source = io.BytesIO()
wb.save(source)
source.seek(0)
md = MarkItDown()
md.register_converter(CaptionedXlsx())
result = md.convert_stream(source, stream_info=StreamInfo(extension=".xlsx"))
assert "Quarterly revenue chart" in result.markdown

The assertion passes on current main (4cc9fa17653d695d64fb9eee5b33d4de55ff84e8) and fails on this head, where result.markdown == "". An instrumented hook is called once on main and zero times here.

Please skip the empty table separately from image processing, and omit the worksheet heading only if neither path produces content. Add a regression for an image-only worksheet with an overridden hook alongside the existing genuinely empty-sheet cases.

Validation on Python 3.12.15/macOS: the existing XLSX suite passes (29 tests), as do the selected library/CLI vectors (33 passed, 6 remote tests skipped). Black 23.7.0 accepts both changed files. The separate image-only regression above fails on the PR and passes on main; the current tests do not cover it.

[OUAO-FRANK]

Thanks for the precise repro — you're right that columns.empty was too blunt, and I had not considered the image hook on an otherwise empty sheet.

Fixed in 4f30b33:

• The sheet's two content channels are now built separately: the cell table (only when columns is non-empty) and the embedded-image output (via images.to_html / _image_to_html).
• The worksheet heading is emitted only when at least one channel produced content, so a genuinely empty sheet stays fully absent (no bare ## name), while an image-only sheet keeps its heading and its hook output.

Added test_image_only_sheet_is_preserved_via_the_hook: a sheet with an embedded image and no cell values, converted through an _ImageConverter whose hook returns "Quarterly revenue chart", asserts that text and the ChartOnly heading both appear.

Verification:

$ pytest tests/test_xlsx.py -q
30 passed
$ black --check src/markitdown/converters/_xlsx_converter.py tests/test_xlsx.py
2 files would be left unchanged

Mutation check: restoring the old columns.empty -> continue guard makes the new image-only test fail with assert 'Quarterly revenue chart' in '', so the regression bites. The four original empty-sheet cases still pass unchanged (the header-only sheet still keeps its heading + delimiter row).

The .xls path is unaffected: it has no image hook, so its columns.empty guard stays as-is.