DEV Community: radin reth

Get update Exchange rate from NBC bank with RoR and Wombat

radin reth — Sat, 16 Dec 2023 01:41:44 +0000

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!

Rails api auth with Grape and Devise JWT

radin reth — Tue, 03 May 2022 09:15:06 +0000

[cover image by Henri Guérin at pixels.com]

I am currently working on developing and api using grape and devise jwt for user user authentication.

Configure devise jwt is pretty straightforward all you need to do is just follow the instruction in the readme.

Install gems

gem 'grape'
gem 'devise'
gem 'devise-jwt'

bundle install

In app/api/api.rb

helpers AuthHelpers
helpers do
  def unauthorized_error!
    error!('Unauthorized', 401)
  end
end

mount V1::UserRegistrationApi

In app/api/auth_helpers.rb

module AuthHelpers
  def current_user
    Warden::JWTAuth::UserDecoder.new.call(
      token, :user, nil
    )
    rescue
      unauthorized_error!
  end

  def token
    auth = headers['Authorization'].to_s
    auth.split.last
  end
end

In app/models/user.rb

class User < ApplicationRecord
include Devise::JWT::RevocationStrategies::Allowlist

devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :validatable,
         **:jwt_authenticatable, jwt_revocation_strategy: self**
end

Generate AllowlistedJwt

bin/rails g model AllowlistedJwt
class CreateAllowlistedJwts < ActiveRecord::Migration[6.1]
  def change
    create_table :allowlisted_jwts do |t|
      t.string :jti, null: false
      t.string :aud
      t.datetime :exp, null: false
      t.references :user, foreign_key: { on_delete: :cascade }, null: false

      t.timestamps
    end

    add_index :allowlisted_jwts, :jti, unique: true
  end
end

In config/initializers/devise.rb

config.jwt do |jwt|
    jwt.secret = Rails.application.credentials.devise_jwt_secret_key!
    jwt.expiration_time = 3600
  end

In app/api/v1/user_registration_api.rb

# frozen_string_literal: true

module V1
  class UserRegistrationApi < Grape::API
    namespace :user do
      namespace :register do
        before do
          @user_mobile_number = UserRegistrationWithMobileNumberService.new params[:mobile_number]
        end

        after do
          header 'Authorization', @user_mobile_number.token
        end

        post do
          @user_mobile_number.register
        end
      end

      put :verify do
        current_user.verify(params[:code])
      end
    end
  end
end

In app/services/user_registration_with_mobile_number_service.rb

class UserRegistrationWithMobileNumberService
  attr_reader :mobile_number, :token

  def initialize(mobile_number)
    @mobile_number = mobile_number
  end

  def register
    user = User.find_or_initialize_by mobile_number: mobile_number
    if user.save
      @token, payload = Warden::JWTAuth::UserEncoder.new.call(user, :user, nil)
      user.on_jwt_dispatch(@token, payload)
      # TODO: UserRegistrationJob.perform_later(user.id)
    end

    user
  end
end

In spec/api/v1/user_registration_api_spec.rb

# frozen_string_literal: true

require 'rails_helper'

RSpec.describe V1::UserRegistrationApi, '/api/v1/user/register' do
  let(:mobile_number) { '01234567' }

  context 'with phone number' do
    it 'creates new user' do
      expect do
        post '/api/v1/user/register', params: { mobile_number: mobile_number }
      end.to change(User, :count).by 1
    end

    it 'responses the new created user' do
      post '/api/v1/user/register', params: { mobile_number: mobile_number }

      expect(json_body).to include mobile_number: mobile_number
      expect(json_body).to include status: 'pending'
      expect(json_body[:code]).to be_present
    end

    it 'responses with jwt authorization token' do
      post '/api/v1/user/register', params: { mobile_number: mobile_number }

      expect(jwt_token).to match /(^[\w-]*\.[\w-]*\.[\w-]*$)/
    end

    context 'when mobile number is already registered' do
      let!(:user) { create(:user, mobile_number: mobile_number)}

      it 'responses with jwt token' do
        post '/api/v1/user/register', params: { mobile_number: mobile_number }

        expect(jwt_token).to match /(^[\w-]*\.[\w-]*\.[\w-]*$)/
      end
    end
  end

  context 'when confirm' do
    before do
      post '/api/v1/user/register', params: { mobile_number: mobile_number }
    end

    context 'with correct code' do
      it 'changes status from pending to confirmed' do
        put '/api/v1/user/verify', params: { code: json_body[:code] }, headers: { 'Authorization': "Bearer #{jwt_token}" }

        expect(json_body(reload: true)[:status]).to eq 'confirmed'
      end
    end

    context 'with wrong code' do
      it 'unable to confirm' do
        put '/api/v1/user/verify', params: { code: 'wrong-code' }, headers: { 'Authorization': "Bearer #{jwt_token}" }

        expect(json_body(reload: true)[:status]).to eq 'pending'
      end
    end

    context 'without authorized jwt token header' do
      it 'responses unauthorized' do
        put '/api/v1/user/verify', params: { code: json_body[:code] }

        expect(response).to be_unauthorized
      end
    end
  end
end

Thanks for reading~

Rails api auth with Grape and Devise JWT

radin reth — Tue, 03 May 2022 09:10:56 +0000

I am currently working on developing and api using grape and devise jwt for user user authentication.

Configure devise jwt is pretty straightforward all you need to do is just follow the instruction in the readme.

with Grape

Install gems

gem 'grape'
gem 'devise'
gem 'devise-jwt'

install the gems

bundle install

in app/api/api.rb

class Api < Grape::API
  helpers AuthHelpers
  helpers do
    def unauthorized_error!
      error!('Unauthorized', 401)
    end
  end

  mount V1::UserRegistrationApi
end

in app/api/auth_helpers.rb

module AuthHelpers
  def current_user
    decoder = Warden::JWTAuth::UserDecoder.new
    decoder.call(token, :user, nil)
  rescue
    unauthorized_error!
  end

  def token
    auth = headers['Authorization'].to_s
    auth.split.last
  end
end

Currently, there 3 revocation strategies that devise jwt provide such as jtimatcher, denylist and allowlist. but for now I am using allowlist strategy.

in app/models/user.rb

class User < ApplicationRecord
include Devise::JWT::RevocationStrategies::Allowlist

devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :validatable,
         :jwt_authenticatable, jwt_revocation_strategy: self
end

Next, we need to generate AllowlistedJwt model

bin/rails g model AllowlistedJwt

Edit the migration file base on your need

class CreateAllowlistedJwts < ActiveRecord::Migration[6.1]
  def change
    create_table :allowlisted_jwts do |t|
      t.string :jti, null: false
      t.string :aud
      t.datetime :exp, null: false
      t.references :user, foreign_key: { on_delete: :cascade }, null: false

      t.timestamps
    end

    add_index :allowlisted_jwts, :jti, unique: true
  end
end

you will need to provide jwt secret. you can generate your own secret key using rails then store it somewhere that you can access to it

bin/rails secret

in config/initializers/devise.rb

Devise.setup do |config|
# other code
config.jwt do |jwt|
    jwt.secret = Rails.application.credentials.devise_jwt_secret_key!
    jwt.expiration_time = 3600
  end
end

in app/api/v1/user_registration_api.rb

module V1
  class UserRegistrationApi < Grape::API
    namespace :user do
      namespace :register do
        before do
          @user_mobile_number = UserRegistrationWithMobileNumberService.new params[:mobile_number]
        end

        # set response headers
        after do
          header 'Authorization', @user_mobile_number.token
        end

        post do
          @user_mobile_number.register
        end
      end

      put :verify do
        current_user.verify(params[:code])
      end
    end
  end
end

in app/services/user_registration_with_mobile_number_service.rb

class UserRegistrationWithMobileNumberService
  attr_reader :mobile_number, :token

  def initialize(mobile_number)
    @mobile_number = mobile_number
  end

  def register
    user = User.find_or_initialize_by mobile_number: mobile_number
    if user.save
      @token, payload = Warden::JWTAuth::UserEncoder.new.call(user, :user, nil)
      user.on_jwt_dispatch(@token, payload)
      # TODO: UserRegistrationJob.perform_later(user.id)
    end

    user
  end
end

in spec/api/v1/user_registration_api_spec.rb

RSpec.describe V1::UserRegistrationApi, '/api/v1/user/register' do
  let(:mobile_number) { '01234567' }

  context 'with phone number' do
    it 'creates new user' do
      expect do
        post '/api/v1/user/register', params: { mobile_number: mobile_number }
      end.to change(User, :count).by 1
    end

    it 'responses the new created user' do
      post '/api/v1/user/register', params: { mobile_number: mobile_number }

      expect(json_body).to include mobile_number: mobile_number
      expect(json_body).to include status: 'pending'
      expect(json_body[:code]).to be_present
    end

    it 'responses with jwt authorization token' do
      post '/api/v1/user/register', params: { mobile_number: mobile_number }

      expect(response.headers['Authorization']).to match /(^[\w-]*\.[\w-]*\.[\w-]*$)/
    end

    context 'when mobile number is already registered' do
      let!(:user) { create(:user, mobile_number: mobile_number)}

      it 'responses with jwt token' do
        post '/api/v1/user/register', params: { mobile_number: mobile_number }

        expect(jwt_token).to match /(^[\w-]*\.[\w-]*\.[\w-]*$)/
      end
    end
  end

  context 'when confirm' do
    before do
      post '/api/v1/user/register', params: { mobile_number: mobile_number }
    end

    context 'with correct code' do
      it 'changes status from pending to confirmed' do
        put '/api/v1/user/verify', params: { code: response.body['code'] }, headers: { 'Authorization': "Bearer #{jwt_token}" }

        expect(json_body(reload: true)[:status]).to eq 'confirmed'
      end
    end

    context 'with wrong code' do
      it 'unable to confirm' do
        put '/api/v1/user/verify', params: { code: 'wrong-code' }, headers: { 'Authorization': "Bearer #{jwt_token}" }

        expect(json_body(reload: true)[:status]).to eq 'pending'
      end
    end

    context 'without authorized jwt token header' do
      it 'responses unauthorized' do
        put '/api/v1/user/verify', params: { code: json_body[:code] }

        expect(response).to be_unauthorized
      end
    end
  end
end

Additional notes:
Try it out in the console

newuser = UserRegistrationWithMobileNumberService.new('+85593555115')
registered_user = newuser.register
jwt = registered_user.allowlisted_jwts.last
payload = { jti: jwt.jti, aud: jwt.aud }

User.jwt_revoked? payload, registered_user
User.revoke_jwt payload, registered_user

Rails active support instrumentation

radin reth — Tue, 07 Sep 2021 06:32:09 +0000

Today I am gonna have a brief introduction about active support instrumentation. We will start from what it really is and how to use it.

Instrumentation provide a HOOK when certain events happen inside rails. Moreover, You can publish your own custom event if you want :)

How it works

It's really easy. All you need to do it listen to event that rails publish.

Below is the activity logs feature that I implement in my current project

I subscribe to process_action.action_controller (rails specific event)
I capture some information and pass to sidekiq's worker to perform some task

# config/initializers/my_event.rb

ActiveSupport::Notifications.subscribe "process_action.action_controller" do |name, started, finished, unique_id, data|
  args = data.slice(:controller, :action, :format, :method, :path, :status)
  args[:payload] = data[:params].except(:action, :controller)
  ActivityLogsWorker.perform_async args
end

Notice that
data is a hash with the following keys

It's simple as that.
for more detail read more on rails official website

cucumber with selenium-webdriver

radin reth — Sat, 04 Sep 2021 07:03:19 +0000

First you have to install web driver that you prefer

For me, I'm using chromedriver

Install selenium-webdriver gem

gem install selenium-webdriver

Then install chromedriver, currently I am using the latest chrome browser version 93

Download chromedriver from chromedriver's website
Choose the driver that support with your browser, eg: ChromeDriver 93.0.4577.15
Extract the zip file and install the package
Move the executable to under /opt/WebDriver/bin (create if the does not exist).

For more detail visit

I get an example from cucumber official website but have a few tweak to get it works in my local machine

# features/search_cheese_on_google.feature
Feature: Visit google using web driver
  Everybody wants to see the result when we search something on google

  Scenario: search for cheese
    Given I am on the google search page
    When I search for "cheese"
    Then the page title will start with "cheese"

In step definition,

# features/step_definitions/webdriver_step.rb
require 'rubygems'
require 'selenium-webdriver'

Selenium::WebDriver::Chrome::Service.driver_path = "/opt/WebDriver/bin/chromedriver"

Given('I am on the google search page') do
  @driver = Selenium::WebDriver.for :chrome
  @driver.get "http://google.com"
end

When('I search for {string}') do |string|
  element = @driver.find_element name: "q"
  element.send_keys "cheese"
  element.submit
end

Then('the page title will start with {string}') do |expected_result|
  wait = Selenium::WebDriver::Wait.new timeout: 10
  wait.until { @driver.title.downcase.start_with? "cheese" }
  puts "Page title is #{@driver.title}"
  @driver.close
  expect(@driver.title).to include expected_result
end

run

cucumber

You would the result something like this

Well done!

Travis ci with Secure Environment variable

radin reth — Wed, 01 Sep 2021 11:54:43 +0000

Install travis

gem install travis
travis login --pro --github-token {GITHUBTOKEN}

Generate GITHUBTOKEN goto:
https://github.com/settings/tokens

For private projects:

user:email (read-only)
read:org (read-only)
repo

For open source projects:

user:email (read-only)
read:org (read-only)
repo_deployment
repo:status
write:repo_hook

travis encrypt SENTRY_DSN="get from sentry" --add

Embed custom font in Rails 6

radin reth — Wed, 01 Sep 2021 11:52:05 +0000

Embed custom font in rails 6 is a bit tricky, below are the steps in order to embed custom font in rails 6 project especially work it works fine for wicked pdf gem

Include your prefer font in app/assets/fonts/
Update app/assets/config/manifest.js

...
//= link_tree ../fonts

I also create app/assets/stylesheets/embeded_fonts.scss

@font-face {
  font-family: "khmeros_battambang";
  src: font-url("khmeros_battambang.ttf") format("truetype");
}

Import to app/assets/stylesheets/application.scss

@import "embeded_fonts";

Import to layouts/pdf.html.haml

= stylesheet_link_tag "embeded_fonts"
= wicked_pdf_stylesheet_link_tag "pdf"
= wicked_pdf_javascript_pack_tag "pdf"

Call the embedded font

body {
  font-family: 'khmeros_battambang'
}

Embed custom font in Rails 6

radin reth — Tue, 10 Aug 2021 03:21:28 +0000

Embed custom font in rails 6 is a bit tricky, below are the steps in order to embed custom font in rails 6 project especially work it works fine for wicked pdf gem

Include your prefer font in app/assets/fonts/
Update app/assets/config/manifest.js

...
//= link_tree ../fonts

I also create app/assets/stylesheets/embeded_fonts.scss

@font-face {
  font-family: "khmeros_battambang";
  src: font-url("khmeros_battambang.ttf") format("truetype");
}

Import to app/assets/stylesheets/application.scss

@import "embeded_fonts";

Import to layouts/pdf.html.haml

= stylesheet_link_tag "embeded_fonts"
= wicked_pdf_stylesheet_link_tag "pdf"
= wicked_pdf_javascript_pack_tag "pdf"

Call the embedded font

body {
  font-family: 'khmeros_battambang', ...
}

git rebase remaining

radin reth — Thu, 22 Jul 2021 09:13:39 +0000

During rebase we sometimes face conflict files that need to resolve and continue one by one.

but how do we know where we are and how many steps need to resolve?

cat .git/rebase-apply/next
cat .git/rebase-apply/last
cat .git/rebase-apply/original-commit

original answer from awesome people in stackoverflow

Rails broadcast report to telegram dynamically

radin reth — Thu, 22 Jul 2021 08:00:10 +0000

create pdfs/ to store the generated pdf
use cronex gem to describe cron in plain english
create telegram bot using botfather 3.1 get username & token

sending document by URL is not guarantee
mount volume /pdfs

Sidekiq clear

radin reth — Thu, 22 Jul 2021 04:21:23 +0000

Sidekiq::Queue.all.each(&:clear)
Sidekiq::RetrySet.new.clear
Sidekiq::ScheduledSet.new.clear
Sidekiq::DeadSet.new.clear

Git Tag

radin reth — Tue, 20 Jul 2021 10:07:53 +0000

List all tags

git tag

Create new tag

git tag tag_name

Delete tag

git tag -d tag_name

Push specific tag to remote

git push origin branch_name <tag>

Push all local tags to remote

git push origin branch_name --tags