export currency with correct decimal places

CHANGELOG.md

@@ -5,6 +5,11 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Updated
+- GTFS export currency with correct number of decimal places
+
 ## [4.15.7] - 2024-11-14
 
 ### Updated

src/lib/export.ts

@@ -13,7 +13,7 @@ import * as models from '../models/models.ts';
 import { openDb } from './db.ts';
 import { prepDirectory, generateFolderName } from './file-utils.ts';
 import { log, logWarning } from './log-utils.ts';
-import { setDefaultConfig } from './utils.ts';
+import { formatCurrency, setDefaultConfig } from './utils.ts';
 
 import { Config, Model } from '../types/global_interfaces.ts';
 
@@ -117,6 +117,14 @@ export const exportGtfs = async (initialConfig: Config) => {
           if (!routesWithAgencyId || routesWithAgencyId.length === 0) {
             excludeColumns.push('agency_id');
           }
+        } else if (model.filenameBase === 'fare_attributes') {
+          for (const line of lines) {
+            line.price = formatCurrency(line.price, line.currency_type);
+          }
+        } else if (model.filenameBase === 'fare_products') {
+          for (const line of lines) {
+            line.price = formatCurrency(line.amount, line.currency);
+          }
         }
 
         const columns = without(

src/lib/utils.ts

@@ -299,3 +299,28 @@ export function getDayOfWeekFromDate(date: number): string {
 
   return DAYS_OF_WEEK[dateObj.getDay()];
 }
+
+/**
+ * Formats a numeric value according to the decimal precision rules of the specified currency,
+ * without any currency symbols or separators.
+ * @param value The numeric value to format (e.g., 10.5)
+ * @param currency The ISO 4217 currency code (e.g., 'USD', 'JPY', 'EUR')
+ * @returns The formatted string with appropriate decimal places
+ *          Examples:
+ *          - formatCurrency(10.5, 'USD') => '10.50'    // USD uses 2 decimal places
+ *          - formatCurrency(10.5, 'JPY') => '10'       // JPY uses 0 decimal places
+ *          - formatCurrency(10.523, 'BHD') => '10.523' // BHD uses 3 decimal places
+ */
+export function formatCurrency(value: number, currency: string) {
+  const parts = new Intl.NumberFormat(undefined, {
+    style: 'currency',
+    currency,
+  }).formatToParts(value);
+
+  const integerPart =
+    parts.find((part) => part.type === 'integer')?.value ?? '0';
+  const fractionPart =
+    parts.find((part) => part.type === 'fraction')?.value ?? '';
+
+  return `${integerPart}${fractionPart !== '' ? `.${fractionPart}` : ''}`;
+}