Get update Exchange rate from NBC bank with RoR and Wombat

I was assigned a task that do exchange currency from US dollar into Khmer riel.

The exchange rate is based on NBC ( National Bank of Cambodia). Unfortunately, the NBC website does not provide provide any Api to get the exchange rate so I am decided to do crawling.

First, I am using sidekiq-cron to perform the crawling every 3 hours. Then, I use wombat gem to perform the crawling. Once, It receives the updated exchange, the system will update and calculate it as Khmer riel.

exchange_rate_spider.rb

## Crawling NBC With OpenSSL verification on(default)
# raise <SSL_connect returned=1 errno=0 state=error: certificate verify failed>

## Disable OpenSSL verfication
# https://github.com/sparklemotion/mechanize/issues/375
# server doesn't provide intermediate certificate to OpenSSL
# Wombat.crawl { mechanize.verify_mode = OpenSSL::SSL::VERIFY_NONE }

module Spider
  class ExchangeRateSpider
    include Wombat::Crawler

    base_url 'https://www.nbc-website.org.kh'
    path '/english/economic_research/exchange_rate_path.php'

    usd_to_khr xpath: '//tr[2]/td/font', &:to_f
  end
end

exchange_rate_job.rb

class ExchangeRateJob < ApplicationJob
  queue_as :default

  def perform
    Setting.instance.update!(usd_to_khr: spider.crawl['usd_to_khr'])
  end

  private

  def spider
    return @spider unless @spider.nil?

    @spider ||= Spider::ExchangeRateSpider.new
    @spider.mechanize.verify_mode = OpenSSL::SSL::VERIFY_NONE
    @spider
  end
end

schedule.yml

exchange_rate_job:
  cron: 'every 3 hours'
  class: 'ExchangeRateJob'
  status: enabled
  description: 'updates exchange rate from NBC'

Thank you for your reading!