Building Extractable Libraries in Rail - Railsconf

Build better libraries in Rails! Talk given at Railsconf 2013

Transcript

1. Building Extractable Libraries in Rails
2. Hello There! I’m @patricksroberts. I work at @iorahealth. I co-organize @bostonrb.
3. The Duality of a Rails Developer
4. Ruby is driven by <3
5. Our best practices change with our sense of beauty
6. Our ecosystem is driven by the many ways to solve problems
7. Rails is driven by Conventions
8. Rails frees us from making many tedious decisions
9. The freedom from decisions allows us unparalleled productivity
10. /lib is the Battlefield
11. I believe it can benefit from some conventions
12. In order to ship more code I believe it can benefit from some conventions
13. Namespace All The Things No Rails Application has a User class right??
14. Avoid the Autoload Trap Maintain explicit entry points into your library code using initializers
15. Use the Configuration Pattern Keep credentials as far away from your library code as possible
16. Isolate Interaction with your Domain Use DCI at the glue points of your application code
17. Namespace All The Things
18. # lib/twitter_user.rb class TwitterUser def initialize(user) @user = user end end # lib/twitter_profile.rb class TwitterProfile def initialize(twitter_user, image_url) @user = twitter_user @image_url = image_url end end
19. # lib/papa_smurf.rb class PapaSmurf end # lib/sleepy_smurf.rb class SleepySmurf end # lib/ninja_smurf.rb class NinjaSmurf end
20. # lib/smurf.rb module Smurf class Papa end class Sleepy end class Ninja end end
21. Avoiding the Autoload Trap
22. Rails 3 brought a wonderful convention for removing /lib from automatically being loaded on application boot...
23. ... however our first instinct is to do this: # config/application.rb # Custom directories with classes and modules you want to be autoloadable. config.autoload_paths += %W(#{config.root}/lib) Let’s try something different!
24. # config/initializers/twitter_wrangler.rb require_relative ‘../lib/twitter_wrangler’ # lib/twitter_wrangler.rb require ‘twitter_wrangler/authentication’ require ‘twitter_wrangler/authorization’ module TwitterWrangler end Combined with...
25. We have created a namespace and setup a proper layout when we need to extract our code outside the application into a gem. ... in ten seconds or less :)
26. Hide Your Credentials From Your Library
27. It’s so simple to do this: # lib/twitter_wrangler.rb module TwitterWrangler OAUTH_KEY = ‘ABCDEFG1234ZXYZB2324’ end Or even this: # lib/twitter_wrangler.rb module TwitterWrangler OAUTH_KEY = ENV[‘TWITTER_KEY’] end
28. But we already have an entry point for our library code. So let’s exploit the heck out of it!
29. # config/initializers/twitter_wrangler.rb require_relative ‘../lib/twitter_wrangler’ TwitterWrangler.configure do |config| config.oauth_key = ENV[:twitter_oauth_key] end
30. # config/initializers/twitter_wrangler.rb require_relative ‘../lib/twitter_wrangler’ TwitterWrangler.configure do |config| config.oauth_key = ENV[:twitter_oauth_key] end
31. # config/initializers/twitter_wrangler.rb require_relative ‘../lib/twitter_wrangler’ TwitterWrangler.configure do |config| config.oauth_key = ENV[:twitter_oauth_key] end
32. # config/initializers/twitter_wrangler.rb require_relative ‘../lib/twitter_wrangler’ TwitterWrangler.configure do |config| config.oauth_key = ENV[:twitter_oauth_key] end
33. # lib/twitter_wrangler/configuration.rb module TwitterWrangler class Configuration < Struct.new(:oauth_key) end class << self attr_accessor :configuration end def self.configure self.configuration ||= Configuration.new yield(configuration) if block_given? end end
34. # lib/twitter_wrangler/configuration.rb module TwitterWrangler class Configuration < Struct.new(:oauth_key) end class << self attr_accessor :configuration end def self.configure self.configuration ||= Configuration.new yield(configuration) if block_given? end end
35. # lib/twitter_wrangler/configuration.rb module TwitterWrangler class Configuration < Struct.new(:oauth_key) end class << self attr_accessor :configuration end def self.configure self.configuration ||= Configuration.new yield(configuration) if block_given? end end
36. # lib/twitter_wrangler/configuration.rb module TwitterWrangler class Configuration < Struct.new(:oauth_key) end class << self attr_accessor :configuration end def self.configure self.configuration ||= Configuration.new yield(configuration) if block_given? end end
37. # lib/twitter_wrangler/configuration.rb module TwitterWrangler class Configuration < Struct.new(:oauth_key) end class << self attr_accessor :configuration end def self.configure self.configuration ||= Configuration.new yield(configuration) if block_given? end end
38. With one additional, boilerplate class we’ve established a separation of credential concerns
39. Keeping Your Domain Models Focused
40. Prescriptions Queueing Authorization Authentication Timeouts Caching BMI Appointments
41. Web App body mass index tweet called Library Authorization Twitter message Authentication Queueing
42. ROLE
43. # lib/twitter_wrangler/tweeting_patient.rb module TwitterWrangler::TweetingPatient def bmi_twitter_message “Today my BMI is #{body_mass_index} and I’m #{percent_of_body_mass_index_goal} from my goal of #{body_mass_index_goal}!” end end
44. A Brief Interlude on Test Doubles
45. # lib/twitter_wrangler/support/fake_patient.rb class FakePatient def body_mass_index;27;end def percent_of_body_mass_index_goal;”95%”;end def body_mass_index_goal;25;end end Option #1 - The Fake Class
46. Option #2 - OpenStruct! patient = OpenStruct.new(body_mass_index: 27, percent_of_body_mass_index_goal: ’95%’, body_mass_index_goal: 25)
47. Option #3 - Mock patient = mock(body_mass_index: 27, percent_of_body_mass_index_goal: ’95%’, body_mass_index_goal: 25)
48. # spec/twitter_wrangler/tweeting_patient_spec.rb describe TweetingPatient do let(:patient) { FakePatient.new } before { patient.extend TweetingPatient } describe ‘#bmi_twitter_message’ do let(:tweet) { patient.bmi_twitter_message } it ‘crafts a lovely tweet’ do expect(tweet).to include ‘Today my BMI is...’ end end end
49. # spec/twitter_wrangler/tweeting_patient_spec.rb describe TweetingPatient do let(:patient) { FakePatient.new } before { patient.extend TweetingPatient } describe ‘#bmi_twitter_message’ do let(:tweet) { patient.bmi_twitter_message } it ‘crafts a lovely tweet’ do expect(tweet).to include ‘Today my BMI is...’ end end end
50. # spec/twitter_wrangler/tweeting_patient_spec.rb describe TweetingPatient do let(:patient) { FakePatient.new } before { patient.extend TweetingPatient } describe ‘#bmi_twitter_message’ do let(:tweet) { patient.bmi_twitter_message } it ‘crafts a lovely tweet’ do expect(tweet).to include ‘Today my BMI is...’ end end end
51. # spec/twitter_wrangler/tweeting_patient_spec.rb describe TweetingPatient do let(:patient) { FakePatient.new } before { patient.extend TweetingPatient } describe ‘#bmi_twitter_message’ do let(:tweet) { patient.bmi_twitter_message } it ‘crafts a lovely tweet’ do expect(tweet).to include ‘Today my BMI is...’ end end end
52. CONTEXT
53. # lib/twitter_wrangler/bmi_twitter_update.rb module TwitterWrangler class BMITwitterUpdate < Struct.new(:patient) def call Queue.push tweeting_patient.bmi_twitter_message end private def tweeting_patient @tweeting_patient ||= patient.extend TweetingPatient end end end
54. # lib/twitter_wrangler/bmi_twitter_update.rb module TwitterWrangler class BMITwitterUpdate < Struct.new(:patient) def call Queue.push tweeting_patient.bmi_twitter_message end private def tweeting_patient @tweeting_patient ||= patient.extend TweetingPatient end end end
55. # lib/twitter_wrangler/bmi_twitter_update.rb module TwitterWrangler class BMITwitterUpdate < Struct.new(:patient) def call Queue.push tweeting_patient.bmi_twitter_message end private def tweeting_patient @tweeting_patient ||= patient.extend TweetingPatient end end end
56. # lib/twitter_wrangler/bmi_twitter_update.rb module TwitterWrangler class BMITwitterUpdate < Struct.new(:patient) def call Queue.push tweeting_patient.bmi_twitter_message end private def tweeting_patient @tweeting_patient ||= patient.extend TweetingPatient end end end
57. # lib/twitter_wrangler/bmi_twitter_update.rb module TwitterWrangler class BMITwitterUpdate < Struct.new(:patient) def call Queue.push tweeting_patient.bmi_twitter_message end private def tweeting_patient @tweeting_patient ||= patient.extend TweetingPatient end end end
58. # spec/twitter_wrangler/bmi_twitter_update_spec.rb describe BMITwitterUpdate do describe ‘#call’ do let(:patient) { mock() } let(:update) { BMITwitterUpdate.new(patient) } before { Queue.stubs(:push) } it ‘extends TweetingPatient’ do update.call expect(patient).to have_received(:extend).with TweetingPatient end it ‘queues the twitter message’ do update.call expect(Queue).to have_received(:push).with patient.bmi_twitter_message end end end
59. # spec/twitter_wrangler/bmi_twitter_update_spec.rb describe BMITwitterUpdate do describe ‘#call’ do let(:patient) { mock() } let(:update) { BMITwitterUpdate.new(patient) } before { Queue.stubs(:push) } it ‘extends TweetingPatient’ do update.call expect(patient).to have_received(:extend).with TweetingPatient end it ‘queues the twitter message’ do update.call expect(Queue).to have_received(:push).with patient.bmi_twitter_message end end end
60. # spec/twitter_wrangler/bmi_twitter_update_spec.rb describe BMITwitterUpdate do describe ‘#call’ do let(:patient) { mock() } let(:update) { BMITwitterUpdate.new(patient) } before { Queue.stubs(:push) } it ‘extends TweetingPatient’ do update.call expect(patient).to have_received(:extend).with TweetingPatient end it ‘queues the twitter message’ do update.call expect(Queue).to have_received(:push).with patient.bmi_twitter_message end end end
61. # spec/twitter_wrangler/bmi_twitter_update_spec.rb describe BMITwitterUpdate do describe ‘#call’ do let(:patient) { mock() } let(:update) { BMITwitterUpdate.new(patient) } before { Queue.stubs(:push) } it ‘extends TweetingPatient’ do update.call expect(patient).to have_received(:extend).with TweetingPatient end it ‘queues the twitter message’ do update.call expect(Queue).to have_received(:push).with patient.bmi_twitter_message end end end
62. # spec/twitter_wrangler/bmi_twitter_update_spec.rb describe BMITwitterUpdate do describe ‘#call’ do let(:patient) { mock() } let(:update) { BMITwitterUpdate.new(patient) } before { Queue.stubs(:push) } it ‘extends TweetingPatient’ do update.call expect(patient).to have_received(:extend).with TweetingPatient end it ‘queues the twitter message’ do update.call expect(Queue).to have_received(:push).with patient.bmi_twitter_message end end end
63. # spec/twitter_wrangler/bmi_twitter_update_spec.rb describe BMITwitterUpdate do describe ‘#call’ do let(:patient) { mock() } let(:update) { BMITwitterUpdate.new(patient) } before { Queue.stubs(:push) } it ‘extends TweetingPatient’ do update.call expect(patient).to have_received(:extend).with TweetingPatient end it ‘queues the twitter message’ do update.call expect(Queue).to have_received(:push).with patient.bmi_twitter_message end end end
64. GLUE
65. # app/controllers/bmi_controller.rb class BmiController < ApplicationController def create bmi = patient.bmis.create(:bmi) Resque.enqueue :bmi_twitter_update_job, patient.id respond_with bmi end private def patient @patient ||= current_user.patients.find(:patient_id) end end
66. # app/jobs/bmi_twitter_update_job.rb class BmiTwitterUpdateJob @queue = :twitter def self.perform_job(patient_id) patient = Patient.find(patient_id) BMITwitterUpdate.new(patient).call end end
67. RECAP
68. Treat Your Lib Directory Like a Temple
69. Remove Configuration Nightmares
70. Protect Domain Interactions
71. Thanks!