Mo Money Mo Problems (with Ruby)
summary
Don't use floats for money; store amounts as integer cents or accept BigDecimal's memory cost. Use deterministic rounding like round half to even (banker's rounding). Run captures asynchronously with background jobs (ActiveJob or similar) and serialize related steps with transactions or Mutex locks so captures and payouts remain atomic. Keep per-transaction ledgers read-only, persist exchange rates for multi-currency work, and abstract gateway code (Stripe, PayPal, Braintree) behind a payment-source interface.
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chapters (9)
- 0:00Introduction
- 2:12Handling money in databases
- 4:20Rounding and currency
- 10:48Using the Money gem
- 12:56Security and background jobs
- 15:41Concurrency and integrity
- 18:23Timing and logging
- 20:26System architecture
- 22:25Fraud detection and close
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