Make `FieldTypes` a `Map` to preserve column order by manzt · Pull Request #9279 · marimo-team/marimo

manzt · 2026-04-20T16:36:39Z

Column names that parse as non-negative integers (e.g. "2000", "2010") were hoisted to the front in numeric order when FieldTypes was a plain Record<string, DataType> since ECMAScript's OrdinaryOwnPropertyKeys iterates integer-indexed keys before string keys.

Fixes #9269. Column names that parse as non-negative integers (e.g. `"2000"`, `"2010"`) were hoisted to the front in numeric order when `FieldTypes` was a plain `Record<string, DataType>` — ECMAScript's `OrdinaryOwnPropertyKeys` iterates integer-indexed keys before string keys. `Map` preserves insertion order for all keys and keeps O(1) lookup.

vercel · 2026-04-20T16:36:44Z

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Project	Deployment	Actions	Updated (UTC)
marimo-docs	Ready	Preview, Comment	Apr 20, 2026 4:36pm

codecov · 2026-04-20T16:39:12Z

Bundle Report

Changes will increase total bundle size by 225.11kB (0.9%) ⬆️. This is within the configured threshold ✅

Detailed changes

Bundle name	Size	Change
marimo-esm	25.1MB	225.11kB (0.9%) ⬆️

Affected Assets, Files, and Routes:

view changes for bundle: marimo-esm

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
`assets/cells-*.js`	59 bytes	704.0kB	0.01%
`assets/index-*.js`	3.62kB	605.92kB	0.6%
`assets/index-*.css`	386 bytes	362.67kB	0.11%
`assets/JsonOutput-*.js`	2.21kB	342.32kB	0.65%
`assets/edit-*.js`	1 bytes	329.61kB	0.0%
`assets/glide-*.js`	-44 bytes	251.07kB	-0.02%
`assets/add-*.js`	7 bytes	192.76kB	0.0%
`assets/layout-*.js`	-311 bytes	185.6kB	-0.17%
`assets/cell-*.js`	3 bytes	183.15kB	0.0%
*`assets/reveal-.js`** (New)	165.6kB	165.6kB	100.0% 🚀
*`assets/swiper-.js`** (New)	116.4kB	116.4kB	100.0% 🚀
*`assets/reveal-.css`** (New)	54.08kB	54.08kB	100.0% 🚀
`assets/file-*.js`	50 bytes	49.4kB	0.1%
`assets/panels-*.js`	6 bytes	45.36kB	0.01%
`assets/session-*.js`	-9 bytes	24.99kB	-0.04%
`assets/state-*.js`	46 bytes	24.45kB	0.19%
`assets/home-*.js`	132 bytes	21.86kB	0.61%
`assets/purify.es-*.js`	16 bytes	21.05kB	0.08%
*`assets/swiper-.css`** (New)	15.12kB	15.12kB	100.0% 🚀
`assets/run-*.js`	-735 bytes	9.74kB	-7.02%
`assets/column-*.js`	-659 bytes	6.53kB	-9.16%
*`assets/mermaid-.core-B0EhnNjP.js`** (New)	2.38kB	2.38kB	100.0% 🚀
*`assets/slide-.js`** (New)	615 bytes	615 bytes	100.0% 🚀
`assets/slides-*.css`	-15.1kB	305 bytes	-98.02%
`assets/slides-*.js`	-116.37kB	0 bytes	-100.0%
~~*`assets/mermaid-.core-Blvy2Lmj.js`*~~ (Deleted)*	-2.38kB	0 bytes	-100.0% 🗑️

Files in assets/index-*.js:

./src/plugins/impl/DataEditorPlugin.tsx → Total Size: 5.81kB

Files in assets/JsonOutput-*.js:

./src/components/data-table/column-summary/column-summary.tsx → Total Size: 6.04kB
./src/components/data-table/types.ts → Total Size: 800 bytes
./src/components/data-table/column-summary/chart-spec-model.tsx → Total Size: 13.97kB

Files in assets/glide-*.js:

./src/plugins/impl/data-editor/glide-data-editor.tsx → Total Size: 19.0kB
./src/plugins/impl/data-editor/data-utils.ts → Total Size: 2.42kB

Copilot

Pull request overview

Fix column-order instability for digit-only column names (e.g. "2000", "2010") by changing FieldTypes from a plain object to an ordered Map, avoiding ECMAScript integer-key reordering during iteration.

Changes:

Change FieldTypes to Map<string, DataType> and update toFieldTypes accordingly.
Update Data Editor and column summary/chart codepaths to use Map APIs (.get, .has, iteration).
Update/add Vitest coverage, including a regression test for insertion order with digit-string column names.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
frontend/src/plugins/impl/data-editor/glide-data-editor.tsx	Iterates `columnFields` as a `Map` and switches lookups to `.get`/`.has`.
frontend/src/plugins/impl/data-editor/data-utils.ts	Updates `modifyColumnFields` to operate on `Map` (insert/remove/rename).
frontend/src/plugins/impl/data-editor/tests/data-utils.test.ts	Adjusts fixtures/assertions for `Map`-based `FieldTypes`.
frontend/src/plugins/impl/DataEditorPlugin.tsx	Initializes `columnFields` as a `Map` and converts to `Record` only for Vega CSV parsing.
frontend/src/components/data-table/types.ts	Redefines `FieldTypes` as `Map` and updates `toFieldTypes`.
frontend/src/components/data-table/column-summary/column-summary.tsx	Guards stats rendering when `type` is missing.
frontend/src/components/data-table/column-summary/chart-spec-model.tsx	Uses `Map.get` for `fieldTypes` and handles missing type when building specs.
frontend/src/components/data-table/tests/types.test.ts	Adds regression test ensuring `toFieldTypes` preserves insertion order for digit-string keys.
frontend/src/components/data-table/tests/chart-spec-model.test.ts	Updates test fixtures to use `Map`-based `FieldTypes`.

Copilot · 2026-04-20T16:42:17Z

  const columns: ModifiedGridColumn[] = useMemo(() => {
    const columns: ModifiedGridColumn[] = [];
-    for (const [columnName, fieldType] of Object.entries(columnFields)) {
+    for (const [columnName, fieldType] of columnFields) {
      const editable =
        editableColumns === "all" || editableColumns.includes(columnName);


Switching columnFields to a Map preserves insertion order for columns, but index-based column operations (e.g. delete) can now diverge from removeColumn, which picks the key by Object.keys(row) ordering. For digit-string column names ("2000"), Object.keys will reorder keys, so deleting column N may remove the wrong property from each row. Prefer removing columns by name (derive const columnName = columns[columnIdx].title) and delete that property, or change removeColumn to accept a column name / explicit key order rather than relying on Object.keys.

Copilot · 2026-04-20T16:42:18Z

  const { error } = useAsyncData(async () => {
    const withoutExternalTypes = toFieldTypes(props.fieldTypes ?? []);

    // If we already have the data, return it


This comment says "If we already have the data, return it", but the async loader always loads/sets localData and doesn't have an early-return path based on existing state. Either remove the misleading line or implement the intended guard (e.g. skip loading when data is already populated and props.data hasn’t changed).

Suggested change

// If we already have the data, return it

// Use the provided rows directly when `props.data` is already an array.

Copilot · 2026-04-20T16:42:18Z

+      const newEntries: Array<[string, DataType]> = [
        ...entries.slice(0, columnIdx),
        [newColumnName, dataType || "string"],


In the rename case, if dataType is omitted this code sets the renamed column’s type to "string". However BulkEdit.Rename edits (applied in glide-data-editor.tsx) don’t include a dataType, so rehydrating/applying initial rename edits will silently change the column’s type (e.g. number -> string). Consider preserving the existing type at columnIdx when dataType is undefined, only overriding when an explicit dataType is provided.

Suggested change

const newEntries: Array<[string, DataType]> = [

...entries.slice(0, columnIdx),

[newColumnName, dataType || "string"],

const existingDataType = entries[columnIdx]?.[1];

const newEntries: Array<[string, DataType]> = [

...entries.slice(0, columnIdx),

[newColumnName, dataType ?? existingDataType ?? "string"],

github-actions · 2026-04-20T20:39:13Z

🚀 Development release published. You may be able to view the changes at https://marimo.app?v=0.23.2-dev63

manzt added 2 commits April 20, 2026 12:11

Add failing test for data_editor column reorder

b135a20

Copilot AI review requested due to automatic review settings April 20, 2026 16:36

manzt added the bug Something isn't working label Apr 20, 2026

manzt requested a review from kirangadhave April 20, 2026 16:36

vercel Bot deployed to Preview April 20, 2026 16:36 View deployment

Copilot started reviewing on behalf of manzt April 20, 2026 16:37 View session

manzt mentioned this pull request Apr 20, 2026

Columns named with string rep of integers (eg "2010") ALWAYS appearing before other columns #9269

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Copilot AI reviewed Apr 20, 2026

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mscolnick approved these changes Apr 20, 2026

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manzt merged commit d075706 into main Apr 20, 2026
34 of 35 checks passed

manzt deleted the push-opupxqpylnow branch April 20, 2026 20:34

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Make `FieldTypes` a `Map` to preserve column order#9279

Make `FieldTypes` a `Map` to preserve column order#9279
manzt merged 2 commits intomainfrom
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	// If we already have the data, return it
	// Use the provided rows directly when `props.data` is already an array.

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