Class: Money::RatesStore::HistoricalRedis

Inherits:
Object
  • Object
show all
Defined in:
lib/money/rates_store/historical_redis.rb

Overview

Exchange rates cache implemented with Redis.

All cached rates are relative to the given base_currency. It stores Hash es with keys formatted as namespace:base_currency:quote_currency . These hashes contain ISO dates as keys with base currency rates as values.

Examples

If currency is the Redis namespace we used in the constructor, USD is the base currency, and we’re looking for HUF rates, they can be found in the currency:USD:HUF key, and their format will be

{
  "2016-05-01": "0.272511002E3", # Rates are stored as BigDecimal Strings
  "2016-05-02": "0.270337998E3",
  "2016-05-03": "0.271477498E3"
}

Instance Method Summary collapse

Constructor Details

#initialize(base_currency, redis_url, namespace) ⇒ HistoricalRedis

Parameters

  • base_currency - The base currency relative to which all rates are stored

  • redis_url - The URL of the Redis server

  • namespace - Namespace with which to prefix all Redis keys



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# File 'lib/money/rates_store/historical_redis.rb', line 50

def initialize(base_currency, redis_url, namespace)
  @base_currency = base_currency
  @redis = Redis.new(url: redis_url)
  @namespace = namespace
end

Instance Method Details

#add_rates(currency_date_rate_hash) ⇒ Object

Adds historical rates in bulk

Parameters

currency_date_rate_hash - A Hash of exchange rates, broken down by currency and date. See the example for details.

Errors

  • Raises ArgumentError when the base currency is included in currency_date_rate_hash with rate other than 1.

  • Raises Money::RatesStore::RequestFailed when the Redis request fails

Examples

Assuming USD is the base currency

rates = {
  'EUR' => {
    '2015-09-10' => 0.11, # 1 USD = 0.11 EUR
    '2015-09-11' => 0.22
  },
  'GBP' => {
    '2015-09-10' => 0.44, # 1 USD = 0.44 GBP
    '2015-09-11' => 0.55
  }
}
store.add_rates(rates)



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# File 'lib/money/rates_store/historical_redis.rb', line 83

def add_rates(currency_date_rate_hash)
  if !currency_date_rate_hash[@base_currency.iso_code].nil? &&
     !currency_date_rate_hash[@base_currency.iso_code].values.all? { |r| r == 1 }

    raise ArgumentError, "When base currency #{@base_currency.iso_code} is included "\
                         "in given Hash #{currency_date_rate_hash}, its rate should  "\
                         'be equal to 1'
  end

  @redis.pipelined do
    currency_date_rate_hash.each do |iso_currency, iso_date_rate_hash|
      k = key(iso_currency)
      @redis.mapped_hmset(k, iso_date_rate_hash)
    end
  end
rescue Redis::BaseError => e
  raise RequestFailed, "Error while storing rates - #{e.message} - "\
                       "rates: #{currency_date_rate_hash}"
end

#get_rates(currency) ⇒ Object

Returns a Hash of rates for all cached dates for the given currency.

Parameters

  • currency - The quote currency for which we request all the cached rates. This is a Money::Currency object.

Examples

store.get_rates(Money::Currency.new('GBP'))
# => {"2017-01-01"=>#<BigDecimal:7fa19ba27260,'0.809782E0',9(18)>, "2017-01-02"=>#<BigDecimal:7fa19ba27210,'0.814263E0',9(18)>, "2017-01-03"=>#<BigDecimal:7fa19ba271c0,'0.816721E0',9(18)>, ...



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# File 'lib/money/rates_store/historical_redis.rb', line 113

def get_rates(currency)
  k = key(currency.iso_code)
  iso_date_rate_hash = @redis.hgetall(k)

  iso_date_rate_hash.each do |iso_date, rate_string|
    iso_date_rate_hash[iso_date] = rate_string.to_d
  end
rescue Redis::BaseError => e
  raise RequestFailed, 'Error while retrieving rates for '\
                          "#{currency} - #{e.message}"\
end