Price Fetching

Basic Usage

Command-Line Interface

# Fetch latest prices for all assets
bean-price ledger.beancount

# Fetch historical prices
bean-price --date=2024-01-15 ledger.beancount

# Fetch specific symbols
bean-price -e "USD:google/NASDAQ:AAPL" "USD:yahoo/VTSAX"

Price Source Configuration

Commodity Declarations

; Stock with single price source
2024-01-01 commodity AAPL
  price: "USD:google/NASDAQ:AAPL"

; Currency with multiple sources
2024-01-01 commodity EUR
  price: "USD:google/CURRENCY:EURUSD,yahoo/EURUSD"

; Asset with multiple quote currencies
2024-01-01 commodity GBP
  price: "USD:yahoo/GBPUSD CAD:yahoo/GBPCAD"

Source String Format

<quote-currency>:<module>/[^]<symbol>

Components:
- quote-currency: Currency for price (USD, EUR, etc.)
- module: Price fetcher implementation
- symbol: Exchange-specific identifier

Price Fetching Methods

Direct Sources

; Google Finance
USD:google/NASDAQ:AAPL    # Stock
USD:google/NYSEARCA:VTI   # ETF
USD:google/CURRENCY:EURUSD # Currency

; Yahoo Finance
USD:yahoo/AAPL           # Stock
USD:yahoo/VTSAX          # Mutual Fund

Inverted Sources

; Invert fetched price
USD:google/^CURRENCY:USDCAD  # CAD price from USD/CAD rate

; With --swap-inverted option
2024-01-15 price USD 1.32759 CAD  # Instead of CAD 0.75324 USD

Fallback Sources

; Try multiple sources in order
2024-01-01 commodity GBP
  price: "USD:google/CURRENCY:GBPUSD,yahoo/GBPUSD"

Cache Management

# Disable caching
bean-price --no-cache ledger.beancount

# Clear existing cache
bean-price --clear-cache ledger.beancount

Price Fetching Modes

Commodity Selection

# Default: Only active holdings
bean-price ledger.beancount

# Include inactive commodities
bean-price --inactive ledger.beancount

# Include undeclared commodities
bean-price --undeclared ledger.beancount

# Include everything
bean-price --all ledger.beancount

Diagnostic Options

# Show what would be fetched
bean-price --dry-run ledger.beancount

# Detailed logging
bean-price -vv ledger.beancount

Custom Source Implementation

Source Class Interface

from beancount.prices import source

class Source(source.Source):
    def get_latest_price(self, ticker):
        """Fetch latest price."""
        # Implementation

    def get_historical_price(self, ticker, time):
        """Fetch historical price."""
        # Implementation

Source Registration

2024-01-01 commodity CUSTOM
  price: "USD:my.price.module/SYMBOL"

Best Practices

1. Price Organization

; Group price sources by type
2024-01-01 commodity STOCK1
  name: "Public Stock"
  price: "USD:google/NASDAQ:STOCK1"

2024-01-01 commodity FUND1
  name: "Mutual Fund"
  price: "USD:yahoo/FUND1"

2. Price Validation

; Add balance assertions after important prices
2024-01-15 price STOCK1 100.00 USD
2024-01-15 balance Assets:Investment:STOCK1 10 STOCK1 @ 100.00 USD

3. Error Handling

; Use multiple sources for reliability
2024-01-01 commodity MAJOR_STOCK
  price: "USD:google/NASDAQ:STOCK,yahoo/STOCK,custom/STOCK"

This guide provides a comprehensive overview of Beancount's price fetching capabilities while maintaining technical accuracy.