How to Implement Multi-Currency Support in FlutterFlow

1const functions = require('firebase-functions');
2const admin = require('firebase-admin');
3const axios = require('axios');
4
5exports.refreshExchangeRates = functions.pubsub
6  .schedule('0 6 * * *')
7  .timeZone('UTC')
8  .onRun(async () => {
9    const apiKey = process.env.EXCHANGE_RATE_API_KEY;
10    const base = 'USD';
11    const url = `https://v6.exchangerate-api.com/v6/${apiKey}/latest/${base}`;
12
13    const response = await axios.get(url);
14    const rates = response.data.conversion_rates;
15
16    const db = admin.firestore();
17    const batch = db.batch();
18
19    const supportedCurrencies = ['USD', 'EUR', 'GBP', 'JPY', 'CAD', 'AUD', 'INR', 'BRL'];
20
21    for (const code of supportedCurrencies) {
22      if (rates[code]) {
23        const ref = db.collection('currencies').doc(code);
24        batch.update(ref, {
25          rate_to_usd: rates[code],
26          updated_at: admin.firestore.FieldValue.serverTimestamp(),
27        });
28      }
29    }
30
31    await batch.commit();
32    return null;
33  });

1import 'package:intl/intl.dart';
2
3String formatPrice(
4  int priceInUsdCents,
5  String currencyCode,
6  double rateToUsd,
7) {
8  // Convert cents to dollars, then to target currency
9  final double usdAmount = priceInUsdCents / 100.0;
10  final double displayAmount = usdAmount * rateToUsd;
11
12  // Map currency codes to locales for correct formatting
13  const Map<String, String> currencyLocales = {
14    'USD': 'en_US',
15    'EUR': 'de_DE',
16    'GBP': 'en_GB',
17    'JPY': 'ja_JP',
18    'CAD': 'en_CA',
19    'AUD': 'en_AU',
20    'INR': 'hi_IN',
21    'BRL': 'pt_BR',
22  };
23
24  final String locale = currencyLocales[currencyCode] ?? 'en_US';
25
26  // JPY has no decimal places
27  final int decimalDigits = currencyCode == 'JPY' ? 0 : 2;
28
29  final formatter = NumberFormat.currency(
30    locale: locale,
31    symbol: '',
32    decimalDigits: decimalDigits,
33  );
34
35  final symbols = {
36    'USD': r'$', 'EUR': '€', 'GBP': '£',
37    'JPY': '¥', 'CAD': r'CA$', 'AUD': r'A$',
38    'INR': '₹', 'BRL': r'R$',
39  };
40
41  final symbol = symbols[currencyCode] ?? currencyCode + ' ';
42  return '$symbol${formatter.format(displayAmount)}';
43}

1// Cloud Function — create Stripe Checkout Session
2exports.createCheckoutSession = functions.https.onCall(async (data, context) => {
3  const { priceInUsdCents, currencyCode, successUrl, cancelUrl } = data;
4  const userId = context.auth?.uid;
5  if (!userId) throw new functions.https.HttpsError('unauthenticated', 'Login required');
6
7  // Fetch current rate from Firestore (never trust client-sent rate)
8  const currencyDoc = await admin.firestore()
9    .collection('currencies').doc(currencyCode).get();
10  const rateToUsd = currencyDoc.data()?.rate_to_usd ?? 1.0;
11
12  const usdAmount = priceInUsdCents / 100;
13  const displayAmount = usdAmount * rateToUsd;
14
15  // Stripe uses smallest unit — JPY has no cents
16  const stripeAmount = currencyCode === 'JPY'
17    ? Math.round(displayAmount)
18    : Math.round(displayAmount * 100);
19
20  const session = await stripe.checkout.sessions.create({
21    payment_method_types: ['card'],
22    line_items: [{
23      price_data: {
24        currency: currencyCode.toLowerCase(),
25        unit_amount: stripeAmount,
26        product_data: { name: data.productName },
27      },
28      quantity: 1,
29    }],
30    mode: 'payment',
31    success_url: successUrl,
32    cancel_url: cancelUrl,
33  });
34
35  return { sessionId: session.id, url: session.url };
36});