rusackas commented on code in PR #42601:
URL: https://github.com/apache/superset/pull/42601#discussion_r3709753764
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superset-frontend/src/utils/downloadAsPivotExcel.ts:
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@@ -17,12 +17,84 @@
* under the License.
*/
import { utils, writeFile } from 'xlsx';
+import type { WorkSheet } from 'xlsx';
+
+// ISO 8601 date (and optional time) form, e.g. "2024-01-01" or
+// "2024-01-01 00:00:00". This layout is unambiguous under any locale
+// (unlike "1/2/2024", which means different dates depending on the
+// reader), so it's safe to restore as a native Excel date.
+const ISO_DATE_RE = /^(\d{4})-(\d{2})-(\d{2})(?:[
T](\d{2}):(\d{2}):(\d{2}))?$/;
+
+// `raw: true` (used below) keeps every table cell as text, so ordinary
+// numbers and dates lose their native Excel type along with the
+// locale-formatted values. A cell's text is only restored to a real number
+// or date when it is unambiguous under any locale: a plain number that
+// round-trips losslessly through Number() (e.g. "42" or "-3.5"), or an
+// ISO 8601 date/datetime string. Restoring those can't reintroduce the
+// misparsing raw: true guards against. Anything else (grouped thousands,
+// percent suffixes, trailing zero padding, other D3_FORMAT output, etc.)
+// stays as text, exactly as rendered.
+function restoreUnambiguousNumbers(sheet: WorkSheet): void {
+ Object.keys(sheet).forEach(cellRef => {
+ if (cellRef.startsWith('!')) {
+ return;
+ }
+ const cell = sheet[cellRef];
+ if (!cell || cell.t !== 's' || typeof cell.v !== 'string') {
+ return;
+ }
+ const isoMatch = cell.v.match(ISO_DATE_RE);
+ if (isoMatch) {
+ const [y, mo, d, h, mi, s] = isoMatch
+ .slice(1)
+ .map((part: string | undefined) => Number(part ?? 0));
+ // SheetJS serializes a cell's Date via its absolute (UTC) epoch time,
+ // not its local calendar fields, so building this from local
+ // components would silently shift the exported value by the host's
+ // UTC offset (e.g. midnight in a positive-offset timezone would
+ // export as the previous day). Constructing - and validating - via
+ // UTC keeps the exported date/time identical to the source text
+ // regardless of the host's timezone.
+ const date = new Date(Date.UTC(y, mo - 1, d, h, mi, s));
+ // The Date constructor rolls invalid components over into the next
+ // unit (e.g. day 40 becomes the 10th of the following month, minute
+ // 60 becomes the top of the next hour) instead of rejecting them, so
+ // confirm every part - date and time - round-trips before trusting
+ // the result.
+ const isValid =
+ date.getUTCFullYear() === y &&
+ date.getUTCMonth() === mo - 1 &&
+ date.getUTCDate() === d &&
+ date.getUTCHours() === h &&
+ date.getUTCMinutes() === mi &&
+ date.getUTCSeconds() === s;
+ if (isValid) {
+ cell.t = 'd';
+ cell.v = date;
+ return;
+ }
+ }
+ const value = Number(cell.v);
+ if (cell.v !== '' && Number.isFinite(value) && String(value) === cell.v) {
+ cell.t = 'n';
+ cell.v = value;
+ }
Review Comment:
Same tradeoff as the numeric-restoration thread above — no column metadata
to tell a dimension label from a measure, and the round-trip check already
limits this to plain numbers/ISO dates that render identically either way.
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