Bodu.Financial.ExchangeRates.Yahoo 0.7.1

Bodu.Financial.ExchangeRates.Yahoo

API stability — Preview. The public API surface is largely settled but is still being finalized ahead of the 1.0 release and may change; breaking changes can land in a minor version until then.

A Bodu.Financial exchange-rate provider backed by the Yahoo Finance chart REST service.

It fetches the Yahoo Finance v8/finance/chart/{symbol} endpoint, parses the JSON response, and serves the results as Bodu.Financial.ExchangeRates.ExchangeRate values through the standard IDatedRateProvider and IRateProvider contracts — so it composes with Money.ConvertTo, the caching and aggregating providers, and the rest of the Bodu.Financial FX stack. It is a logical sister to Bodu.Financial.ExchangeRates.Rba: the same interfaces and DI shape, a different data source.

using Bodu.Financial.ExchangeRates;

// The provider builds and owns its HttpClient from the options; dispose it to release the client.
using var provider = new YahooRateProvider(new YahooRateProviderOptions());

// Warm a pair for a range (recommended), then look rates up synchronously.
await provider.LoadPairAsync("AUD", "USD", new DateOnly(2023, 1, 1), new DateOnly(2026, 6, 30));

RateLookupResult usd = provider.GetRate("AUD", "USD", new DateOnly(2023, 1, 3));

// Read a whole range at once. The result is an IReadOnlyList<ExchangeRate> that also reports
// the requested window (RequestedStartDate/RequestedEndDate) and the observed span.
RateRangeResult series =
    await provider.GetRatesAsync("AUD", "JPY", new DateOnly(2026, 1, 1), new DateOnly(2026, 6, 12));

// The latest available spot rate.
decimal latest = provider.GetRate("EUR", "GBP");

Behaviour

• Arbitrary pairs. Yahoo serves any pair through the {FROM}{TO}=X ticker convention (for example, AUDUSD=X, EURGBP=X), so there is no base-currency restriction. The inverse direction is served directly or, if only the reverse series is loaded, inverted.
• Daily bars. The chart interval is fixed at one day; the date range is supplied per call through LoadPairAsync / GetRatesAsync.
• Loading. Call LoadPairAsync to warm the in-memory store. A synchronous lookup that misses an un-fetched pair will block to fetch a window around the requested date only when AllowSynchronousNetworkAccess is enabled (it is false by default, so the provider serves a snapshot of already-loaded data and a synchronous miss does not reach the network).
• No provider-local disk cache. The Yahoo provider fetches over HTTP and keeps only an in-memory store of the pairs and windows it has fetched this session; it does not persist anything to disk. For durable caching across processes, compose it with the generic caching provider — AddCachedRateProvider<…> from the Bodu.Financial.ExchangeRates.Caching package — rather than a provider-local cache.

HTTP client and lifetime

The provider is IDisposable and offers two construction styles:

• new YahooRateProvider(options, ...) — the provider builds, owns, and disposes its own HttpClient, created via RateProviderHttpClientFactory.Create from the configured user agent and timeout. Dispose the provider (for example with using) to release the client.
• new YahooRateProvider(httpClient, options, ...) — you supply the client and own its lifetime; the provider never disposes a client it did not create. This is the form the *.DependencyInjection package uses, backed by IHttpClientFactory.

Endpoint configuration

YahooRateProviderOptions is centred on configuring the REST endpoint:

The Yahoo provider has no EnableDiskCache / CacheDirectory / CacheExpiry options: it fetches over HTTP with no provider-local disk cache. Use the generic Bodu.Financial.ExchangeRates.Caching package (AddCachedRateProvider<…>) when you need caching.

Dependency injection

The package ships its own AddYahooExchangeRates registration in the Bodu.Financial.ExchangeRates namespace — there is no separate *.DependencyInjection package.

Logging

The provider logs through Microsoft.Extensions.Logging. Pass an ILogger to the constructor, or let the *.DependencyInjection package wire one for you (category Bodu.Financial.ExchangeRates.YahooRateProvider). When no logger is supplied it defaults to NullLogger.Instance, so logging is entirely opt-in and free when unused.

The levels follow the conventions used by Microsoft.Extensions.Http, EF Core, and the Azure SDK — the completed download is the one Information line per fetch, payload detail is Trace, and degraded paths are Warning. Every level is individually configurable on YahooRateProviderOptions:

// Quieten the per-fetch line and turn off per-observation tracing entirely.
var options = new YahooRateProviderOptions
{
    DownloadCompletedLogLevel = LogLevel.Debug,
    ObservationIngestedLogLevel = LogLevel.None,
};

The default verbosity is deliberately low: at Information you see one line per pair/chart loaded; at Debug you additionally see when downloads start; only at Trace do you get a line per rate observation (which can be hundreds per chart — keep it for targeted debugging).

Part of the Bodu utility library.