feat(xlsx): write and read a row format on RowDef by ronistrom · Pull Request #612 · productdevbook/hucre

ronistrom · 2026-10-20T18:49:05Z

Closes #601

What was missing

RowDef had height, hidden, outlineLevel and collapsed, but nothing for a row-level format. Excel writes a row formatted as a whole as <row s="N" customFormat="1"> (ECMA-376 Part 1 §18.3.1.73), and the reader dropped both attributes. So a row format in an Excel file was lost on a read-write round trip, and there was no way to write one. ColumnDef.style has done the column equivalent (<col style="N">) since #439.

The issue's input, a height and a bold style on row 2:

await writeXlsx({
  sheets: [{
    name: "S",
    rows: [["Name", "Qty"], ["Total", 3]],
    rowDefs: new Map([[1, { height: 20, style: { font: { bold: true } } }]]),
  }],
})

<!-- before -->
<row r="2" ht="20" customHeight="1"><c r="A2" t="s"><v>2</v></c><c r="B2"><v>3</v></c></row>
<!-- after -->
<row r="2" ht="20" customHeight="1" s="1" customFormat="1"><c r="A2" t="s" s="1"><v>2</v></c><c r="B2" s="1"><v>3</v></c></row>

Reading that file back with readStyles: true:

before: rowDefs.get(1) = {"height":20}
after:  rowDefs.get(1) = {"height":20,"style":{"font":{"bold":true}}}

And test/fixtures/excel-styleonly.xlsx, which Excel wrote with four formatted rows (rows 3 and 4 have no cells, so the <row> is the only place their format lives):

before: rowDefs = []
after:  rowDefs = [[0, {style: {font: {bold: true, …}}}],
                   [1, {style: {numFmt: "0.00", fill: {pattern: "solid", fgColor: {rgb: "DDEBF7"}, …}}}],
                   [2, …same…], [3, …same…]]

What landed

RowDef.style?: CellStyle, with a doc comment.
Writer. rowAttributes() in worksheet-writer.ts is shared by writeXlsx and the streaming RowSerializer, so both writers emit s and customFormat="1". They are written only when the style resolves to a non-default xf, the same rule <col style> follows, so a row definition with no style writes exactly the bytes it did before. A test pins that output. A row that has a format and no cells still gets a self-closing <row … s customFormat/>. writeWorksheetXml now uses hasRowAttributes() instead of its own inline copy of the check.
The row style is also put on the row's cells. This follows the column precedent, and it is what Excel itself writes: the fixture has the row's s on every cell in the row. Any cell in that row with no style of its own gets the row style. That covers cells from rows, from data[] (including the generated header row), and from a cells override that adds a cell to the row. A cell that has its own style keeps it.
A row style wins over a column style on a cell that neither styles directly, and the column's numFmt doesn't apply there either. The order is cell, then row, then column, which is also what Excel does for an empty cell where a styled row crosses a styled column (checked in Excel, below). The streaming writer used to merge a column's numFmt into any style a cell ended up with. It no longer does that to a row style, so writeXlsx and writeXlsxStream produce the same cell styles. A test checks both writers.
Reader. When customFormat is 1/true and styles are being read, s becomes RowDef.style. It is resolved and cloned once per row, as column styles are, so editing one row's style doesn't change another's. A bare s without customFormat is ignored, because the spec says s only applies to the row when customFormat is set. Without readStyles, the row comes back without the style, like everything else that depends on styles.
cloneSheet deep-copies the row style.
customFormat is removed from the REVIEWED map in scripts/spec-coverage.mjs. docs/SPEC-COVERAGE.md is regenerated: customFormat moves out of the reviewed list, and the counts go 31 → 30 and 644 → 645. I checked that the script reproduces main's committed file before the change and this one after.
docs/PARITY.md: row and column definitions are at XLSX parity "a row or column format included", and ODS lists row formats among what neither direction models. In the README, a short paragraph and example for rowDefs style, and a "row formats" entry in the ODS table. SheetBuilder.rowDef and the StreamWriterOptions.rowDefs doc comments name the new field.
The parity register's rowDefs probe now includes a numFmt-only style, which keeps it clear of A style font without name/size does not inherit defaultFont #594's font change. The cloneSheet register now has a row style and checks that the copy doesn't share it.

Tests: 14 of the new or extended tests fail against main:

11 of the 14 in the new test/row-style.test.ts
the Excel fixture test in real-files.test.ts
the parity register round trip
the cloneSheet detach check

The three in row-style.test.ts that pass on main all check something that should not happen: no customFormat on a row without a style, a bare s being ignored, and no style without readStyles. bun run test passes on Node 24, with 241 files and 10,713 tests.

After review, a second commit fixes two older gaps the row format made reachable:

Rows past the data. writeXlsx stopped at the last row of data, so a formatted row below it, or a sheet with only rowDefs, got no <row>. Those definitions are now written after the data, in row order.
Rows without r. r is optional on <row>. The reader read a row's height, hidden flag, outline level, collapsed flag and format from r alone, so a row without it lost all of them. It now uses the row's position, as it already did for the row's cells.

Three of the four new tests fail without that commit. The coverage test that pinned the old drop now expects the flags kept. bun run test passes, with 241 files and 10,717 tests. writeXlsxStream still writes only the rows it is given.

Checked in Excel

In Excel for Mac. Formats were read from Excel itself, through its scripting interface, and checked against screenshots.

Writing. The issue's case, with row 2 given a 24 pt height and a bold yellow style. Before this change, row 2 was only taller. After it, row 2 is bold on yellow all the way across, including the empty cells E2 and Z2 that hucre never wrote. The file opens without a repair prompt.
Reading a file Excel wrote. I formatted the row 5 header in Excel (bold, with a fill), saved, and read the file with readStyles: true. main returns no rowDefs. This branch returns row 5 with font.bold and the fill.
Precedence. A sheet written by this branch, with columns B and D styled red and italic, and row 2 styled yellow and bold:
- B2 is a cell hucre writes. It gets the row style.
- D2 is an empty cell where the two cross, with no <c>, so Excel decides. Excel also shows it yellow and bold.
- D3, which has only the column, is red.
So "row wins over column" matches Excel for an unstyled cell. Columns B and D came out hidden in that file. That is A column with a style or outlineLevel but no width is hidden in Excel #603, a separate bug on main where a <col> with a style but no width is zero wide. It does not affect the formats Excel reports.

Not verified

LibreOffice and Google Sheets. Not opened.
Windows Excel. Only Excel for Mac was checked.
Rows without a style index. RowDef.style: {} still gets its own xf (index 1), as {} already does on a cell or column. It is not treated as "no format".

RowDef had height, hidden, outline level and collapsed but no format, so a row Excel formatted as a whole (`<row s="N" customFormat="1">`, ECMA-376 Part 1 §18.3.1.73) was dropped on read and could not be written at all. ColumnDef.style has carried the column equivalent since productdevbook#439. RowDef.style is now written by both writeXlsx and writeXlsxStream through the shared rowAttributes(), as `s` plus `customFormat="1"`, and only when the style resolves to a non-default xf, so a row definition without a style writes exactly what it wrote before. A row that has a format and no cells still gets its self-closing `<row>`. Following the column precedent, and what Excel itself writes, the row style is also stamped onto the cells in that row that have no style of their own. Where a column style covers the same cell, the row's wins, number format included; the streaming writer no longer folds a column numFmt into a row format, so the two writers agree. The cell > row > column order is not verified in Excel. The reader takes `s` into RowDef.style when `customFormat` is 1/true and styles are being read, with a per-row copy as for columns; a bare `s` is ignored as the spec says. cloneSheet deep-copies the row style. customFormat leaves the spec-coverage REVIEWED list and SPEC-COVERAGE.md is regenerated; PARITY.md and the README say rows carry a format. Closes productdevbook#601

coderabbitai · 2026-10-20T18:49:20Z

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📒 Files selected for processing: 4

src/xlsx/worksheet-writer.ts
src/xlsx/worksheet.ts
test/coverage-xlsx-worksheet.test.ts
test/row-style.test.ts

📝 Walkthrough

Adds RowDef.style support for XLSX row formatting. The writer emits row styles and applies them to eligible cells. The reader restores row styles when customFormat enables them. Tests cover writing, reading, style precedence, and cloning.

Changes: Row-level formatting

Layer / File(s)	Summary
Row style contract and cloning `src/_types.ts`, `src/builder.ts`, `src/sheet-ops.ts`, `test/clone-sheet-coverage.test.ts`, `README.md`, `docs/PARITY.md`	Adds `RowDef.style?: CellStyle`, documents row-style behavior, and clones row style objects when cloning sheets.
XLSX row-style writing `src/xlsx/stream-writer.ts`, `src/xlsx/worksheet-writer.ts`, `test/row-style.test.ts`	Registers row styles for row attributes. Applies row styles to cells unless a cell has an explicit style. Row styles take precedence over column styles. Styled rows can be emitted without cells.
XLSX row-style reading and round-trip tests `src/xlsx/worksheet.ts`, `test/row-style.test.ts`, `test/real-files.test.ts`, `test/xlsx-write-read-parity.test.ts`, `scripts/spec-coverage.mjs`, `docs/SPEC-COVERAGE.md`	Reads non-empty row styles when `customFormat` is enabled and style reading is active. Adds row-style reader and round-trip coverage, and updates SpreadsheetML coverage records.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Feature

Sequence Diagram(s)

sequenceDiagram
  participant RowDef
  participant WorksheetWriter
  participant StylesCollector
  participant WorksheetXML
  participant WorksheetParser
  RowDef->>WorksheetWriter: Provide row style
  WorksheetWriter->>StylesCollector: Register row style
  StylesCollector-->>WorksheetWriter: Return style index
  WorksheetWriter->>WorksheetXML: Emit row style attributes and styled cells
  WorksheetXML->>WorksheetParser: Provide row attributes
  WorksheetParser-->>RowDef: Store cloned style when customFormat is enabled

Suggested reviewers: productdevbook

Merge Risk: 🔵 Low · up to 92348

Row-level XLSX formatting works for common files, but three edge cases remain. Row formats are lost when reading rows without explicit row numbers. Formats set on rows beyond the written data are also dropped. In styled rows, the streaming and regular writers can format explicitly styled cells differently. These issues are narrow, and each has a small fix; addressing them before merge is recommended but not blocking.

Pre-merge checks: 4 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 70.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 10 functions across 10 files. (3 skipped:…	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely describes the main change: adding support to write and read row formats through RowDef.
Linked Issues check		Issue `#601` is open and directly linked. The PR adds `RowDef.style?: CellStyle`, writes row `s` and `customFormat="1"` through shared regular and streaming writer paths, reads gated row styles when `re…
Out of Scope Changes check		The changes stay connected to `#601`. Cell-style propagation implements row-wide formatting behavior. Clone support prevents shared row styles. Documentation, parity data, spec-coverage data, and tests …

Full details: Linked Issues check

Explanation

Issue #601 is open and directly linked. The PR adds RowDef.style?: CellStyle, writes row s and customFormat="1" through shared regular and streaming writer paths, reads gated row styles when readStyles is enabled, and updates the parity register. The supplied test summary covers row XML, writer parity, reader round trips, style precedence, empty rows, and clone behavior.

Full details: Out of Scope Changes check

Explanation

The changes stay connected to #601. Cell-style propagation implements row-wide formatting behavior. Clone support prevents shared row styles. Documentation, parity data, spec-coverage data, and tests document or verify the feature. The evidence shows no unrelated product behavior.

Full details: Docstring Coverage

Explanation

Docstring coverage is 70.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 10 functions across 10 files. (3 skipped: 3 unsupported.)

Resolution

Write docstrings for the functions missing them to satisfy the coverage threshold.

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Inline comments:
Review comments at @src/xlsx/stream-writer.ts:
- Line 314: Update the condition around the column numFmt merge to exclude
explicitly styled cells when rowStyle is present, preventing colDef.numFmt from
being applied when own is true and the cell style lacks numFmt. Keep column
formatting available for unstyled cells and cells without a styled row, and
preserve parity with the buffered writer.

Review comments at @src/xlsx/worksheet-writer.ts:
- Line 527: Extend row serialization in the regular and streaming writers beyond
resolved data rows to include the highest row definition that has row attributes
requiring an emitted element, including styled definitions and sheets containing
only rowDefs. Update the boundary logic around hasRowDef and the corresponding
streaming row-serialization path without allocating intervening cell grids,
while preserving existing output for ordinary data rows.

Review comments at @src/xlsx/worksheet.ts:
- Line 565: Update the row number calculation in the worksheet row-style parsing
logic to use the already computed currentRowNum rather than attrs["r"], ensuring
rows without an explicit r attribute retain their style; preserve the existing
one-based-to-zero-based adjustment.

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📒 Files selected for processing: 14

README.md
docs/PARITY.md
docs/SPEC-COVERAGE.md
scripts/spec-coverage.mjs
src/_types.ts
src/builder.ts
src/sheet-ops.ts
src/xlsx/stream-writer.ts
src/xlsx/worksheet-writer.ts
src/xlsx/worksheet.ts
test/clone-sheet-coverage.test.ts
test/real-files.test.ts
test/row-style.test.ts
test/xlsx-write-read-parity.test.ts

💤 Files with no reviewable changes: 1

scripts/spec-coverage.mjs

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Two gaps the review of productdevbook#601 found, both older than the row format but now reachable through it: - writeXlsx stopped its row loop at the last row of data, so a row definition past it — a formatted row below a table, or a sheet with only rowDefs — got no <row>. The definitions past the data are now written after it, in row order, without visiting the rows between. - `r` is optional on <row>. The reader numbered the row's cells from its position but read its height, hidden, outline, collapsed and format from `r` alone, which is NaN without it, so all of them were dropped. They now use the same row number as the cells. The coverage test that pinned the old behaviour now expects the flags kept. writeXlsxStream is unchanged: it writes the rows it is given, and a definition for a row it never receives is a separate change. Refs productdevbook#601

coderabbitai Bot reviewed Oct 20, 2026

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Comment thread src/xlsx/stream-writer.ts

Comment thread src/xlsx/worksheet-writer.ts

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ronistrom mentioned this pull request Oct 20, 2026

writeXlsx and writeXlsxStream format a styled cell in a formatted column differently #616

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feat(xlsx): write and read a row format on RowDef - #612

feat(xlsx): write and read a row format on RowDef#612
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