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带货币宝石的rails缓存(欧盟中央银行)

currency memcached caching ruby ruby-on-rails

holden · 技术社区 · 14 年前

http://github.com/RubyMoney/eu_central_bank

eu_bank ||= EuCentralBank.new
eu_bank.update_rates
#Rails.cache.fetch('rates', :expires_in => 24.hours) { eu_bank.update_rates }
rate = eu_bank.exchange_with(Money.new(100, session[:currency]), "USD").to_f

它有一个功能,可以将费率写入某个文件。。。但我也不确定这是我想要的。我也在使用heroku,它有一个只读文件系统。

eu_bank.save_rates("/some/file/location/exchange_rates.xml")

4 回复 | 直到 14 年前

Peter Sorowka 11 年前

这可以通过使用Rails低级缓存和before_过滤器来实现:

class ApplicationController < ActionController::Base

  before_filter :set_conversion_rates

  def set_conversion_rates

    rates = Rails.cache.fetch "money:eu_central_bank_rates", expires_in: 24.hours do

      Money.default_bank.save_rates_to_s
    end

    Money.default_bank.update_rates_from_s rates

  end
end

此代码将在24小时内下载一次费率,并将结果保存到缓存(无论您使用何种缓存模块),在每次请求时,bank对象都会从缓存中加载费率。

lacco 13 年前

https://github.com/RubyMoney/eu_central_bank/commit/fc6c4a3164ad47747c8abbf5c21df617d2d9e644 是必需的。因为我不想每24小时重新启动我的web进程,所以我在 before_filter (可能更好的方式?)。实际的 Money.default_bank.update_rates 调用可能会移动到重复的resque作业(或其他)。

module MyNamespace
  class Bank
    def self.update_rates_if_changed
      if last_updated.nil? || last_updated + 12.hours <= Time.now
        update_rates
      end
    end

    def self.update_rates
      fetch_rates

      # Take latest available currency rates snapshot
      [0, 1, 2].each do |days|
        date = Date.today - days.days
        next unless Rails.cache.exist?(rate_key(date))

        begin
          rates = Rails.cache.read(rate_key(date))
          Money.default_bank.update_rates_from_s(rates)
        rescue Nokogiri::XML::SyntaxError
          print "error occurred while reading currency rates"
          # our rates seem to be invalid, so clear the cache and retry
          Rails.cache.delete(rate_key(date))
          update_rates
        end

        break
      end
    end

    private
    def self.fetch_rates
      return if Rails.cache.exist?(rate_key)

      print "Updating currency rates ... "
      begin
        Rails.cache.write(rate_key, Money.default_bank.save_rates_to_s)
        puts "finished"
      rescue Exception => ex
        puts "error occurred: #{ex.inspect}"
      end
    end

    def self.rate_key(date = Date.today)
      ["exchange_rates", date.strftime("%Y%m%d")]
    end

    def self.last_updated
      Money.default_bank.last_updated
    end
  end
end

应用程序/控制器/应用程序控制器.rb

class ApplicationController
  before_filter :check_for_currency_updates

  def check_for_currency_updates
    MyNamespace::Bank.update_rates_if_changed
  end
end

配置/初始化器/money.rb

MyNamespace::Bank.update_rates_if_changed

hellvinz 14 年前

Since the amount of data is relatively small you can Marshal.dump eu_bank对象,将其存储在memchache中,有效期为24小时(请参见 this doc ).

每次你需要它的时候,你都会从memchache和Marshal中检索到它并加载它。

如果密钥已过期或已从缓存中消失,则将其重新获取

Laurynas 14 年前

配置/初始化器/money.rb

# Money exchange
::Money.default_bank = ::EuCentralBank.new

EU_CENTRAL_BANK_CACHE = '/tmp/eu_bank_exchange_rates.xml'

# Right now we update exchange rates on app restart. App is restarted daily after logs rotation,
# Should be ok for now.

if (!File.exist?(EU_CENTRAL_BANK_CACHE)) || File.mtime(EU_CENTRAL_BANK_CACHE) < 23.hours.ago
  p "Updating money exchange rates"
  ::Money.default_bank.save_rates(EU_CENTRAL_BANK_CACHE)
end

::Money.default_bank.update_rates(EU_CENTRAL_BANK_CACHE)