opendata/readme.hints.md

OpenData Project Hints

Stocks Module

Overview

The stocks module provides real-time stock price data through various provider implementations. Currently supports Yahoo Finance with an extensible architecture for additional providers.

Architecture

• Provider Pattern: Each stock data source implements the IStockProvider interface
• Service Registry: StockPriceService manages providers with priority-based selection
• Caching: Built-in cache with configurable TTL to reduce API calls
• Fallback Logic: Automatic failover between providers if one fails

Yahoo Finance Provider Notes

• Uses public API endpoints (no authentication required)
• Two main endpoints:
  • /v8/finance/chart/{ticker} - Single ticker with full data
  • /v8/finance/spark?symbols={tickers} - Multiple tickers with basic data
• Response data is in response.body when using smartrequest
• Requires User-Agent header to avoid rate limiting

Usage Example

import { StockPriceService, YahooFinanceProvider } from '@fin.cx/opendata';

const stockService = new StockPriceService({ ttl: 60000 });
const yahooProvider = new YahooFinanceProvider();
stockService.register(yahooProvider);

const price = await stockService.getPrice({ ticker: 'AAPL' });
console.log(`${price.ticker}: $${price.price}`);

Testing

• Tests use real API calls (be mindful of rate limits)
• Mock invalid ticker 'INVALID_TICKER_XYZ' for error testing
• Clear cache between tests to ensure fresh data
• The spark endpoint may return fewer results than requested

Future Providers

To add a new provider:

1. Create ts/stocks/providers/provider.{name}.ts
2. Implement the IStockProvider interface
3. Register with StockPriceService
4. No changes needed to existing code