.

Author: catamphetamine

CHANGELOG.md

@@ -1,3 +1,8 @@
+5.3.4 / 11.06.2022
+==================
+
+* Added an optional `reason?: string` property of a with-schema parsing error.
+
 5.3.3 / 24.05.2022
 ==================
 

README.md

@@ -157,7 +157,7 @@ const schema = {
 }
 
 readXlsxFile(file, { schema }).then(({ rows, errors }) => {
-  // `errors` list items have shape: `{ row, column, error, value }`.
+  // `errors` list items have shape: `{ row, column, error, reason?, value?, type? }`.
   errors.length === 0
 
   rows === [{
@@ -241,27 +241,34 @@ const { rows, errors } = convertToJson(data, schema)
 ```js
 import { parseExcelDate } from 'read-excel-file'
 
-function ParseExcelError({ children: error }) {
-  // Get a human-readable value.
-  let value = error.value
-  if (error.type === Date) {
-    value = parseExcelDate(value).toString()
-  }
-  // Render error summary.
+function ParseExcelError({ children }) {
+  const { type, value, error, reason, row, column } = children
+
+  // Error summary.
   return (
     <div>
-      <code>"{error.error}"</code>
+      <code>"{error}"</code>
+      {reason && ' '}
+      {reason && <code>("{reason}")</code>}
       {' for value '}
-      <code>"{value}"</code>
+      <code>{stringifyValue(value)}</code>
       {' in column '}
-      <code>"{error.column}"</code>
-      {error.type && ' of type '}
-      {error.type && <code>"{error.type.name}"</code>}
+      <code>"{column}"</code>
+      {type && type.name && ' of type '}
+      {type && type.name && <code>"{type.name}"</code>}
       {' in row '}
-      <code>"{error.row}"</code>
+      <code>{row}</code>
     </div>
   )
 }
+
+function stringifyValue(value) {
+  // Wrap strings in quotes.
+  if (typeof value === 'string') {
+    return '"' + value + '"'
+  }
+  return String(value)
+}
 ```
 </details>
 

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "read-excel-file",
-  "version": "5.3.3",
+  "version": "5.3.4",
   "description": "Read small to medium `*.xlsx` files in a browser or Node.js. Parse to JSON with a strict schema.",
   "module": "index.js",
   "main": "index.cjs",

package.json

@@ -0,0 +1,118 @@
+// XLSX does have "d" type for dates, but it's not commonly used.
+// Instead, it prefers using "n" type for storing dates as timestamps.
+//
+// Whether a numeric value is a number or a date timestamp, it sometimes could be
+// detected by looking at the value "format" and seeing if it's a date-specific one.
+// https://github.com/catamphetamine/read-excel-file/issues/3#issuecomment-395770777
+//
+// The list of generic numeric value "formats":
+// https://xlsxwriter.readthedocs.io/format.html#format-set-num-format
+//
+export default function isDateTimestamp(value, styleId, styles, options) {
+  if (styleId) {
+    const style = styles[styleId]
+    if (!style) {
+      throw new Error(`Cell style not found: ${styleId}`)
+    }
+    if (
+      // Whether it's a "number format" that's conventionally used for storing date timestamps.
+      BUILT_IN_DATE_NUMBER_FORMAT_IDS.indexOf(parseInt(style.numberFormat.id)) >= 0 ||
+      // Whether it's a "number format" that uses a "formatting template"
+      // that the developer is certain is a date formatting template.
+      (options.dateFormat && style.numberFormat.template === options.dateFormat) ||
+      // Whether the "smart formatting template" feature is not disabled
+      // and it has detected that it's a date formatting template by looking at it.
+      (options.smartDateParser !== false && style.numberFormat.template && isDateTemplate(style.numberFormat.template))
+     ) {
+      return true
+    }
+  }
+}
+
+// https://hexdocs.pm/xlsxir/number_styles.html
+const BUILT_IN_DATE_NUMBER_FORMAT_IDS = [14,15,16,17,18,19,20,21,22,27,30,36,45,46,47,50,57]
+
+// On some date formats, there's an "[$-414]" prefix.
+// I don't have any idea what that is.
+//
+// https://stackoverflow.com/questions/4730152/what-indicates-an-office-open-xml-cell-contains-a-date-time-value
+//
+// Examples:
+//
+// * 27 (built-in format) "[$-404]e/m/d"
+// * 164 (custom format) "[$-414]mmmm\ yyyy;@"
+//
+const DATE_FORMAT_WEIRD_PREFIX = /^\[\$-414\]/
+
+// On some date formats, there's an ";@" postfix.
+// I don't have any idea what that is.
+// Examples:
+//
+// * 164 (custom format) "m/d/yyyy;@"
+// * 164 (custom format) "[$-414]mmmm\ yyyy;@"
+//
+const DATE_FORMAT_WEIRD_POSTFIX = /;@$/
+
+function isDateTemplate(template) {
+  // Date format tokens could be in upper case or in lower case.
+  // There seems to be no single standard.
+  // So lowercase the template first.
+  template = template.toLowerCase()
+
+  // On some date formats, there's an "[$-414]" prefix.
+  // I don't have any idea what that is. Trim it.
+  template = template.replace(DATE_FORMAT_WEIRD_PREFIX, '')
+
+  // On some date formats, there's an ";@" postfix.
+  // I don't have any idea what that is. Trim it.
+  template = template.replace(DATE_FORMAT_WEIRD_POSTFIX, '')
+
+  const tokens = template.split(/\W+/)
+  for (const token of tokens) {
+    if (DATE_TEMPLATE_TOKENS.indexOf(token) < 0) {
+      return false
+    }
+  }
+  return true
+}
+
+// These tokens could be in upper case or in lower case.
+// There seems to be no single standard, so using lower case.
+const DATE_TEMPLATE_TOKENS = [
+  // Seconds (min two digits). Example: "05".
+  'ss',
+  // Minutes (min two digits). Example: "05". Could also be "Months". Weird.
+  'mm',
+  // Hours. Example: "1".
+  'h',
+  // Hours (min two digits). Example: "01".
+  'hh',
+  // "AM" part of "AM/PM". Lowercased just in case.
+  'am',
+  // "PM" part of "AM/PM". Lowercased just in case.
+  'pm',
+  // Day. Example: "1"
+  'd',
+  // Day (min two digits). Example: "01"
+  'dd',
+  // Month (numeric). Example: "1".
+  'm',
+  // Month (numeric, min two digits). Example: "01". Could also be "Minutes". Weird.
+  'mm',
+  // Month (shortened month name). Example: "Jan".
+  'mmm',
+  // Month (full month name). Example: "January".
+  'mmmm',
+  // Two-digit year. Example: "20".
+  'yy',
+  // Full year. Example: "2020".
+  'yyyy',
+
+  // I don't have any idea what "e" means.
+  // It's used in "built-in" XLSX formats:
+  // * 27 '[$-404]e/m/d';
+  // * 36 '[$-404]e/m/d';
+  // * 50 '[$-404]e/m/d';
+  // * 57 '[$-404]e/m/d';
+  'e'
+];

source/read/isDateTimestamp.js

@@ -9,6 +9,10 @@ import {
   getCellInlineStringValue
 } from '../xml/xlsx.js'
 
+import {
+  getOuterXml
+} from '../xml/dom.js'
+
 // Example of a `<c/>`ell element:
 //
 // <c>
@@ -54,6 +58,7 @@ export default function parseCell(node, sheet, xml, values, styles, properties,
     column: coords[1],
     value: parseCellValue(value, type, {
       getInlineStringValue: () => getCellInlineStringValue(sheet, node),
+      getInlineStringXml: () => getOuterXml(node),
       getStyleId: () => node.getAttribute('s'),
       styles,
       values,