Module adapters 

External financial data source adapters.

Each adapter is behind a feature flag and follows the same pattern:

1. Enable the feature in Cargo.toml:

   [dependencies]
   finance-query = { version = "2.4", features = ["polygon"] }

2. Initialize once at startup with your API key:

   finance_query::adapters::polygon::init("YOUR_KEY").unwrap();

3. Call any endpoint — all functions are async:

   use finance_query::adapters::polygon::{self, Timespan};
   let bars = polygon::stock_aggregates("AAPL", 1, Timespan::Day, "2024-01-01", "2024-12-31", None).await?;

Available adapters

Feature	Provider	Free tier	Endpoints	Coverage
alphavantage	Alpha Vantage	25 req/day	~100	Stocks, forex, crypto, commodities, economic indicators, 50+ technical indicators
polygon	Polygon.io	5 req/sec	~100	Stocks, options, forex, crypto, indices, futures, economy, analyst data, WebSocket streaming
fmp	Financial Modeling Prep	250 req/day	~100	Fundamentals, DCF/ratings, insider trading, institutional holdings, screener, 60+ exchanges

Quick comparison

• Alpha Vantage: Best free option for technical indicators (50+) and economic data. Lowest rate limits.
• Polygon.io: Tick-level trades/quotes, SEC filings, real-time WebSocket streams. Best for market microstructure.
• FMP: Deepest fundamentals coverage (as-reported financials, DCF, ratings, analyst estimates, earnings transcripts). Best for fundamental analysis.

All adapters share:

• Singleton pattern with init(api_key) / init_with_timeout(api_key, timeout)
• Built-in rate limiting via shared token-bucket limiter
• Error mapping to crate::FinanceError variants
• Full mockito test coverage (no API key needed to run tests)

Modules

alphavantage

Alpha Vantage financial data API (requires alphavantage feature). Alpha Vantage API client for financial data.

fmp

Financial Modeling Prep (FMP) financial data API (requires fmp feature). Financial Modeling Prep API client for financial data.

polygon

Polygon.io financial data API (requires polygon feature). Polygon.io API client for financial data.