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after_initialize_caching

💡 Cache Expensive Computations on Initialization​

If your model runs heavy computations or external API calls on load, use after_initialize plus a thread‑safe memo to avoid repeated work. This is especially useful for app‑wide lookup tables or configurations.

class CurrencyRate < ApplicationRecord
  after_initialize :load_rate_cache

  def load_rate_cache
    @rate_cache ||= fetch_remote_rates
  end

  private

  def fetch_remote_rates
    # expensive HTTP call or complex logic
  end
end

The first instantiation hits the external service, and subsequent loads in the same process fetch from @rate_cache.