feat(automatic-exchange-rates): Add Yahoo Finance as a provider via yfinance

app/apps/currencies/exchange_rates/fetcher.py

@@ -17,6 +17,7 @@ PROVIDER_MAPPING = {
     "frankfurter": providers.FrankfurterProvider,
     "twelvedata": providers.TwelveDataProvider,
     "twelvedatamarkets": providers.TwelveDataMarketsProvider,
+    "yfinance": providers.YFinanceMarketsProvider,
 }
 
 

app/apps/currencies/exchange_rates/providers.py

@@ -503,3 +503,82 @@ class TwelveDataMarketsProvider(ExchangeRateProvider):
                 )
 
         return results
+
+
+class YFinanceMarketsProvider(ExchangeRateProvider):
+    """Fetch market prices for Yahoo Finance symbols using yfinance.
+
+    Currency codes are passed to Yahoo Finance verbatim. For example, use
+    ``PETR4.SA`` for Petrobras on B3 or ``AAPL`` for Apple. The configured
+    exchange currency is treated as the currency of the Yahoo quote.
+    """
+
+    rates_inverted = True
+
+    def __init__(self, api_key: str = None, ticker_factory=None):
+        super().__init__(api_key)
+        self._ticker_factory = ticker_factory
+
+    @classmethod
+    def requires_api_key(cls) -> bool:
+        return False
+
+    def _get_ticker_factory(self):
+        if self._ticker_factory is None:
+            try:
+                import yfinance as yf
+            except ImportError as exc:
+                raise RuntimeError(
+                    "The yfinance package is required for the Yahoo Finance provider."
+                ) from exc
+
+            self._ticker_factory = yf.Ticker
+
+        return self._ticker_factory
+
+    def get_rates(
+        self, target_currencies: QuerySet, exchange_currencies: set
+    ) -> List[Tuple[Currency, Currency, Decimal]]:
+        results = []
+        ticker_factory = self._get_ticker_factory()
+
+        for asset in target_currencies:
+            exchange_currency = asset.exchange_currency
+            if exchange_currency not in exchange_currencies:
+                continue
+
+            try:
+                history = ticker_factory(asset.code).history(
+                    period="5d", interval="1h", auto_adjust=False
+                )
+
+                if history is None or history.empty:
+                    logger.warning(
+                        "YFinanceMarkets: no history returned for %s", asset.code
+                    )
+                    continue
+
+                try:
+                    latest_close = history["Close"].dropna().iloc[-1]
+                except (IndexError, KeyError, TypeError):
+                    logger.warning(
+                        "YFinanceMarkets: no close price returned for %s", asset.code
+                    )
+                    continue
+
+                rate = Decimal(str(latest_close))
+                if not rate.is_finite() or rate <= 0:
+                    logger.warning(
+                        "YFinanceMarkets: invalid close price %r for %s",
+                        latest_close,
+                        asset.code,
+                    )
+                    continue
+
+                results.append((exchange_currency, asset, rate))
+            except Exception as exc:
+                logger.error(
+                    "YFinanceMarkets: error fetching %s: %s", asset.code, exc
+                )
+
+        return results

app/apps/currencies/migrations/0024_alter_exchangerateservice_service_type.py

@@ -0,0 +1,30 @@
+# Generated by Django 5.2.15 on 2026-07-18 17:26
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("currencies", "0023_add_failure_count"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="exchangerateservice",
+            name="service_type",
+            field=models.CharField(
+                choices=[
+                    ("coingecko_free", "CoinGecko (Demo/Free)"),
+                    ("coingecko_pro", "CoinGecko (Pro)"),
+                    ("transitive", "Transitive (Calculated from Existing Rates)"),
+                    ("frankfurter", "Frankfurter"),
+                    ("twelvedata", "TwelveData"),
+                    ("twelvedatamarkets", "TwelveData Markets"),
+                    ("yfinance", "Yahoo Finance"),
+                ],
+                max_length=255,
+                verbose_name="Service Type",
+            ),
+        ),
+    ]

app/apps/currencies/models.py

@@ -105,6 +105,7 @@ class ExchangeRateService(models.Model):
         FRANKFURTER = "frankfurter", "Frankfurter"
         TWELVEDATA = "twelvedata", "TwelveData"
         TWELVEDATA_MARKETS = "twelvedatamarkets", "TwelveData Markets"
+        YFINANCE = "yfinance", "Yahoo Finance"
 
     class IntervalType(models.TextChoices):
         ON = "on", _("On")

app/apps/currencies/tests/test_yfinance_provider.py

@@ -0,0 +1,93 @@
+from decimal import Decimal
+from unittest import TestCase
+
+from apps.currencies.exchange_rates.fetcher import PROVIDER_MAPPING
+from apps.currencies.exchange_rates.providers import YFinanceMarketsProvider
+from apps.currencies.models import ExchangeRateService
+
+
+class _FakeSeries:
+    def __init__(self, values):
+        self._values = values
+
+    def dropna(self):
+        return _FakeSeries([value for value in self._values if value is not None])
+
+    @property
+    def iloc(self):
+        return self
+
+    def __getitem__(self, index):
+        return self._values[index]
+
+
+class _FakeHistory:
+    def __init__(self, close_values):
+        self._close_values = close_values
+        self.empty = not close_values
+
+    def __getitem__(self, field):
+        if field != "Close":
+            raise KeyError(field)
+        return _FakeSeries(self._close_values)
+
+
+class _FakeCurrency:
+    def __init__(self, code, exchange_currency=None):
+        self.code = code
+        self.exchange_currency = exchange_currency
+
+
+class _FakeTicker:
+    def __init__(self, history):
+        self.history_result = history
+        self.history_kwargs = None
+
+    def history(self, **kwargs):
+        self.history_kwargs = kwargs
+        return self.history_result
+
+
+class YFinanceMarketsProviderTests(TestCase):
+    def setUp(self):
+        self.brl = _FakeCurrency("BRL")
+        self.asset = _FakeCurrency("AAPL", exchange_currency=self.brl)
+
+    def test_returns_latest_hourly_close_using_symbol_verbatim(self):
+        ticker = _FakeTicker(_FakeHistory([36.90, None, 37.42]))
+        requested_symbols = []
+
+        def ticker_factory(symbol):
+            requested_symbols.append(symbol)
+            return ticker
+
+        provider = YFinanceMarketsProvider(ticker_factory=ticker_factory)
+
+        rates = provider.get_rates([self.asset], {self.brl})
+
+        self.assertEqual(rates, [(self.brl, self.asset, Decimal("37.42"))])
+        self.assertEqual(requested_symbols, ["AAPL"])
+        self.assertEqual(
+            ticker.history_kwargs,
+            {"period": "5d", "interval": "1h", "auto_adjust": False},
+        )
+
+    def test_passes_brazilian_symbol_verbatim_and_skips_empty_history(self):
+        self.asset.code = "PETR4.SA"
+        ticker = _FakeTicker(_FakeHistory([]))
+        requested_symbols = []
+
+        provider = YFinanceMarketsProvider(
+            ticker_factory=lambda symbol: requested_symbols.append(symbol)
+            or ticker
+        )
+
+        rates = provider.get_rates([self.asset], {self.brl})
+
+        self.assertEqual(rates, [])
+        self.assertEqual(requested_symbols, ["PETR4.SA"])
+
+    def test_is_registered_without_an_api_key(self):
+        self.assertFalse(YFinanceMarketsProvider.requires_api_key())
+        self.assertIs(PROVIDER_MAPPING["yfinance"], YFinanceMarketsProvider)
+        self.assertEqual(ExchangeRateService.ServiceType.YFINANCE, "yfinance")