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!
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