Learning to lib Again

Making the most of the lib directory in a Rails app

Transcript

1. Learning to lib Again Making the Most of the lib Directory in a Rails App Brett Chalupa pdx.rb February 2016
2. pdx.rb, 2016-02-02 Learning to Lib Again 2 Intro Hi, my name is Brett!
3. pdx.rb, 2016-02-02 Learning to Lib Again 3 Intro I develop software at
4. pdx.rb, 2016-02-02 Learning to Lib Again 4 Intro • Programmer for 10 years • Ruby and Rails programmer for 5 years • Organized the Burlington Ruby Conference for three years
5. pdx.rb, 2016-02-02 Learning to Lib Again 5 Intro I recently traded the snow for the rain.
6. pdx.rb, 2016-02-02 Learning to Lib Again 6 Intro Thank you so much for having me!
7. pdx.rb, 2016-02-02 Learning to Lib Again 7 What the heck is this talk about? Let's talk about the lib directory.
8. pdx.rb, 2016-02-02 Learning to Lib Again 8 Why? For years I thought the lib directory in Rails projects was just for rake tasks.
9. pdx.rb, 2016-02-02 Learning to Lib Again 9 Why? These days, the lib directory is where I spend most of my time when working with Rails.
10. pdx.rb, 2016-02-02 Learning to Lib Again 10 Why? It has changed the way I look at Rails, and it has made me a better Rubyist.
11. pdx.rb, 2016-02-02 Learning to Lib Again 11 What lib is for In a gem, lib is where the code goes.
12. pdx.rb, 2016-02-02 Learning to Lib Again 12 What lib is for A simple Ruby gem file structure:
13. pdx.rb, 2016-02-02 Learning to Lib Again 13 What lib is for class Jikan # Prints the time in a way that is not awful. # # Example: # >> Jikan.time # => The time is 6:14 PM # The date is February 7, 2013 def self.time puts "The time is #{Time.now.strftime("%I:%M %p")}." puts "The date is #{Time.now.strftime("%B %d, %Y")}." end end
14. pdx.rb, 2016-02-02 Learning to Lib Again 14 What lib is for In a new Rails project, the lib dir is for rake tasks and assets.
15. pdx.rb, 2016-02-02 Learning to Lib Again 15 What lib is for lib can be used for so much more than rake tasks and assets.
16. pdx.rb, 2016-02-02 Learning to Lib Again 16 What lib is for lib is great for code that does not fit Rails' paradigms.
17. pdx.rb, 2016-02-02 Learning to Lib Again 17 What lib is for Code that is not: • Models • Views • Controllers • Mailers • Jobs*
18. pdx.rb, 2016-02-02 Learning to Lib Again 18 What lib is for So… lib can be used for just about anything!
19. pdx.rb, 2016-02-02 Learning to Lib Again 19 When to use lib Here are some great times to put code in the lib directory.
20. pdx.rb, 2016-02-02 Learning to Lib Again 20 Pre-gem development Put code in lib that feels like it could be its own gem.
21. pdx.rb, 2016-02-02 Learning to Lib Again 21 Pre-gem development Is the code being written something that could potentially be used by other projects?
22. pdx.rb, 2016-02-02 Learning to Lib Again 22 Pre-gem development Would it make a good open source library?
23. pdx.rb, 2016-02-02 Learning to Lib Again 23 Pre-gem development Let's say an app needs to interface with a third- party API to send faxes, called Faxly.
24. pdx.rb, 2016-02-02 Learning to Lib Again 24 Pre-gem development Faxly is a new service and does not have a Ruby gem.
25. pdx.rb, 2016-02-02 Learning to Lib Again 25 Pre-gem development It would be nice there was a gem to make interacting with Faxly's API easier.
26. pdx.rb, 2016-02-02 Learning to Lib Again 26 Pre-gem development For example: faxly_client = Faxly::Client.new( key: 'some-key', secret: 'some-secret' ) faxly_client.send_fax( to: recipient.fax_number, body: 'Hey! Who faxes documents anymore?' )
27. pdx.rb, 2016-02-02 Learning to Lib Again 27 Pre-gem development This is a great use for the lib directory!
28. pdx.rb, 2016-02-02 Learning to Lib Again 28 Pre-gem development The Faxly client code is external to the domain logic of this hypothetical app.
29. pdx.rb, 2016-02-02 Learning to Lib Again 29 Pre-gem development Create a directory in lib called faxly. Within that dir, it is just like building out a Ruby gem.
30. pdx.rb, 2016-02-02 Learning to Lib Again 30 Pre-gem development # lib/faxly/client.rb module Faxly class Client def initialize(key:, secret:) # get a token for making requests end def send_fax(to:, body:) # make the HTTP request to send the fax end end end
31. pdx.rb, 2016-02-02 Learning to Lib Again 31 Pre-gem development It is easier to extract code and tests into a gem when they are independent of Rails.
32. pdx.rb, 2016-02-02 Learning to Lib Again 32 Pre-gem development However, beware of extracting the code into a gem too early.
33. pdx.rb, 2016-02-02 Learning to Lib Again 33 Pre-gem development Well… why not just start the building the Faxly client library as a gem from the start?
34. pdx.rb, 2016-02-02 Learning to Lib Again 34 Pre-gem development The overhead of maintaining a separate gem is usually not worth it from the start.
35. pdx.rb, 2016-02-02 Learning to Lib Again 35 Pre-gem development Private gems require a private gem server or a private Git repo.
36. pdx.rb, 2016-02-02 Learning to Lib Again 36 Pre-gem development Public gems take time and energy to support.
37. pdx.rb, 2016-02-02 Learning to Lib Again 37 Pre-gem development Building a more general use gem for anyone to use is a lot more time consuming and distracting than writing the code that you need.
38. pdx.rb, 2016-02-02 Learning to Lib Again 38 Pre-gem development A separate codebase for a gem means more steps to make changes and get them into the app.
39. pdx.rb, 2016-02-02 Learning to Lib Again 39 Pre-gem development Extract the code into a gem when it is stable, useful to others, and feels right!
40. pdx.rb, 2016-02-02 Learning to Lib Again 40 Jobs Remember the * that was next to Jobs before?
41. pdx.rb, 2016-02-02 Learning to Lib Again 41 Jobs The app/jobs dir is where jobs should go, especially with ActiveJob.
42. pdx.rb, 2016-02-02 Learning to Lib Again 42 Jobs In our app, users can connect the DropCube file sync service to automatically back-up their faxes before they get sent.
43. pdx.rb, 2016-02-02 Learning to Lib Again 43 Jobs class BackupFaxJob < ActiveJob::Base def perform(fax) fax.prep_for_pdf_transformation pdf = PDFWizard.new pdf.main_text = fax.body pdf.header = fax.recipient pdf.footer = fax.user fax_dir = “faxes/#{Date.today.strftime('%Y-%m-%d')}-#{SecureHex.random}.pdf” drop_cube_client = DropCube::Client.new('https://api.dropcube.cool/') drop_cube_client.put_file(pdf, dir: fax_dir) end end
44. pdx.rb, 2016-02-02 Learning to Lib Again 44 Jobs Complex jobs are a code smell.
45. pdx.rb, 2016-02-02 Learning to Lib Again 45 Jobs Have complex jobs delegate to classes in lib.
46. pdx.rb, 2016-02-02 Learning to Lib Again 46 Jobs How would one write tests for that? The #perform method is doing a lot, which makes it difficult to test and debug.
47. pdx.rb, 2016-02-02 Learning to Lib Again 47 Jobs The job should make use of action classes in lib to make the job simpler. class BackupFaxJob < ActiveJob::Base def perform(fax) pdf = FaxBackup::CreatesPDF.new(fax).create FaxBackup::SyncsToDropCube.new(pdf).sync end end
48. pdx.rb, 2016-02-02 Learning to Lib Again 48 Jobs class BackupFaxJob < ActiveJob::Base def perform(fax) fax.prep_for_pdf_transformation pdf = PDFWizard.new pdf.main_text = fax.body pdf.header = fax.recipient pdf.footer = fax.user fax_dir = “faxes/#{Date.today.strftime('%Y-%m-%d')}-#{SecureHex.random}.pdf” drop_cube_client = DropCube::Client.new('https://api.dropcube.cool/') drop_cube_client.put_file(pdf, dir: fax_dir) end end
49. pdx.rb, 2016-02-02 Learning to Lib Again 49 Jobs class BackupFaxJob < ActiveJob::Base def perform(fax) pdf = FaxBackup::CreatesPDF.new(fax).create FaxBackup::SyncsToDropCube.new(pdf).sync end end
50. pdx.rb, 2016-02-02 Learning to Lib Again 50 Jobs Now testing #perform is about expecting a class to create a PDF and another class to sync it. It is up to the tests of each of those classes to determine how that is handled.
51. pdx.rb, 2016-02-02 Learning to Lib Again 51 Jobs Those two files for backing up faxes could live at: • lib/fax_backup/creates_pdf.rb • lib/fax_backup/syncs_to_drop_cube.rb
52. pdx.rb, 2016-02-02 Learning to Lib Again 52 Jobs Create action classes to handle the work for non-trivial jobs.
53. pdx.rb, 2016-02-02 Learning to Lib Again 53 SCFM There is a way of thinking with Rails known as: Skinny controllers, fat models SCFM
54. pdx.rb, 2016-02-02 Learning to Lib Again 54 SCFM The gist of SCFM is that controllers in Rails apps can become very complex at times. SCFM is about removing the complexities of a controller and delegating them to a model.
55. pdx.rb, 2016-02-02 Learning to Lib Again 55 SCFM However, SCFM leads to models that become all-knowing, extremely complex, and hundreds of lines.
56. pdx.rb, 2016-02-02 Learning to Lib Again 56 SCFM Instead of putting a bunch of methods into a model, make use of…
57. pdx.rb, 2016-02-02 Learning to Lib Again 57 SCFM You guessed it, the lib dir!
58. pdx.rb, 2016-02-02 Learning to Lib Again 58 SCFM Similar to the complexities of jobs, controllers should delegate to action classes in lib to do the work.
59. pdx.rb, 2016-02-02 Learning to Lib Again 59 Tickets::Completer module Tickets class Completer def initialize(ticket) @ticket = ticket @project = ticket.project end def complete! return false if ticket.complete? ticket.complete! update_project_status end end end
60. pdx.rb, 2016-02-02 Learning to Lib Again 60 New paradigms in app/ Try to avoid adding new paradigms in the app directory.
61. pdx.rb, 2016-02-02 Learning to Lib Again 61 New paradigms in app/ Some app/ paradigms I seen before: • Services • Presenters • Forms • Queries
62. pdx.rb, 2016-02-02 Learning to Lib Again 62 New paradigms in app/ They are all too generic for their own good.
63. pdx.rb, 2016-02-02 Learning to Lib Again 63 New paradigms in app/ Don't worry about fitting code into a generic noun.
64. pdx.rb, 2016-02-02 Learning to Lib Again 64 New paradigms in app/ Create action classes that specifically describe what the code does and the domain it encompasses.
65. pdx.rb, 2016-02-02 Learning to Lib Again 65 New paradigms in app/ Once more and more similar action classes get created, look into refactoring to a more generic approach.
66. pdx.rb, 2016-02-02 Learning to Lib Again 66 New paradigms in app/ When I started using Rails it took me years to understand MVC and what goes where.
67. pdx.rb, 2016-02-02 Learning to Lib Again 67 New paradigms in app/ New generic classifications of code are more difficult to understand than using specific classes.
68. pdx.rb, 2016-02-02 Learning to Lib Again 68 When to use lib Try putting code that doesn't fit nicely into the existing Rails paradigms in lib and see how it goes.
69. pdx.rb, 2016-02-02 Learning to Lib Again 69 How to use lib Using lib with Rails is pretty straightforward.
70. pdx.rb, 2016-02-02 Learning to Lib Again 70 How to use lib The various classes and modules could be required where needed, but that can be a bit tedious.
71. pdx.rb, 2016-02-02 Learning to Lib Again 71 How to use lib require 'secure_hash_generator' require 'fax_formatter' class Fax < ActiveRecord::Base def format FaxFormatter.new( SecureHashGenerator.new.generate ) end end
72. pdx.rb, 2016-02-02 Learning to Lib Again 72 How to use lib Add the following line to config/application.rb: config.paths.add 'lib', eager_load: true
73. pdx.rb, 2016-02-02 Learning to Lib Again 73 How to use lib That autoloads and eagerloads all of the code in the lib directory so it is accessible everywhere.
74. pdx.rb, 2016-02-02 Learning to Lib Again 74 How to use lib require 'secure_hash_generator' require 'fax_formatter' class Fax < ActiveRecord::Base def format FaxFormatter.new( SecureHashGenerator.new.generate ) end end
75. pdx.rb, 2016-02-02 Learning to Lib Again 75 How to use lib class Fax < ActiveRecord::Base def format FaxFormatter.new( SecureHashGenerator.new.generate ) end end
76. pdx.rb, 2016-02-02 Learning to Lib Again 76 Organizing lib The lib dir is a blank canvas at the start, which can be intimidating.
77. pdx.rb, 2016-02-02 Learning to Lib Again 77 Organizing lib Create directories (and namespaces) that correspond to different domains and concepts.
78. pdx.rb, 2016-02-02 Learning to Lib Again 78 Organizing lib Most importantly, don't sweat it.
79. pdx.rb, 2016-02-02 Learning to Lib Again 79 Testing code in lib Testing code in lib is very similar to models and other classes.
80. pdx.rb, 2016-02-02 Learning to Lib Again 80 Testing code in lib For RSpec, the spec for lib/faxly/client.rb would live at spec/lib/faxly/client_spec.rb
81. pdx.rb, 2016-02-02 Learning to Lib Again 81 Testing code in lib require 'rails_helper' describe Faxly::Client do subject { described_class.new(creds) } describe '#send_fax' do it 'makes an HTTP request' do expect(HTTPal).to receive(:make_request).with(some_json_blob) subject.send_fax( to: '1-800-123-4567', body: 'Serious business info' ) end end end
82. pdx.rb, 2016-02-02 Learning to Lib Again 82 Testing code in lib With RSpec, running rails generate rspec:install creates two files: 1. spec/spec_helper.rb 2. spec/rails_helper.rb
83. pdx.rb, 2016-02-02 Learning to Lib Again 83 Testing code in lib The spec_helper is for general RSpec configuration that is not specific to Rails.
84. pdx.rb, 2016-02-02 Learning to Lib Again 84 Testing code in lib The rails_helper is for Rails specific RSpec configuration. It requires the spec_helper: require 'spec_helper'
85. pdx.rb, 2016-02-02 Learning to Lib Again 85 Testing code in lib Requiring rails_helper loads the entire Rails environment and every gem required in the Gemfile.
86. pdx.rb, 2016-02-02 Learning to Lib Again 86 Testing code in lib Gemfile: gem 'brakeman' – loads the gem automatically gem 'brakeman', require: false – does not load the gem automatically
87. pdx.rb, 2016-02-02 Learning to Lib Again 87 Testing code in lib require 'rails_helper' describe FaxesController do describe '#create' do it 'creates a fax record' do end end end
88. pdx.rb, 2016-02-02 Learning to Lib Again 88 Testing code in lib Loading up the entire Rails environment is slow and unnecessary when testing code in lib.
89. pdx.rb, 2016-02-02 Learning to Lib Again 89 Testing code in lib When unit testing code in lib that does not depend on Rails, require the spec_helper instead.
90. pdx.rb, 2016-02-02 Learning to Lib Again 90 Testing code in lib require 'spec_helper' require 'faxly/client' describe Faxly::Client do describe '#send_fax' do it 'sends a fax' do end end end
91. pdx.rb, 2016-02-02 Learning to Lib Again 91 Testing code in lib This means faster tests for that file. But how much faster? Let's see with: $ time bundle exec rspec spec/path/to/spec.rb * The app has 28 required gems in the Gemfile.
92. pdx.rb, 2016-02-02 Learning to Lib Again 92 Testing code in lib With rails_helper: ..... Finished in 0.07432 seconds (files took 5.6 seconds to load) 5 examples, 0 failures real 0m6.598s user 0m2.962s sys 0m0.597s
93. pdx.rb, 2016-02-02 Learning to Lib Again 93 Testing code in lib With spec_helper: ..... Finished in 0.04742 seconds (files took 0.29089 seconds to load) 5 examples, 0 failures real 0m0.964s user 0m0.830s sys 0m0.127s
94. pdx.rb, 2016-02-02 Learning to Lib Again 94 Testing code in lib ~ 6.8x faster. Pretty good, right?
95. pdx.rb, 2016-02-02 Learning to Lib Again 95 Testing code in lib With rails_helper with Spring: ..... Finished in 0.05533 seconds (files took 3.17 seconds to load) 5 examples, 0 failures real 0m3.875s user 0m2.720s sys 0m0.558s
96. pdx.rb, 2016-02-02 Learning to Lib Again 96 Testing code in lib Requiring rails_helper is a little better with Spring, but it is still ~4x slower.
97. pdx.rb, 2016-02-02 Learning to Lib Again 97 Testing code in lib When doing TDD, a 4x speed increase makes a big difference.
98. pdx.rb, 2016-02-02 Learning to Lib Again 98 Testing code in lib Note: requiring spec_helper does not make a difference when running the whole test suite because Rails has to be loaded anyways.
99. pdx.rb, 2016-02-02 Learning to Lib Again 99 Testing code in lib Code and gems need to be explicitly required when using spec_helper.
100. pdx.rb, 2016-02-02 Learning to Lib Again 100 A few recent uses Dropbox sync
101. pdx.rb, 2016-02-02 Learning to Lib Again 101 A few recent uses Client for internal API with no gem library
102. pdx.rb, 2016-02-02 Learning to Lib Again 102 A few recent uses Sortable table headers
103. pdx.rb, 2016-02-02 Learning to Lib Again 103 A few recent uses Light-weight AWS S3 client wrapper module Storage class S3File def initialize(key) bucket = ENV['some-bucket'] client = Aws::S3::Client.new @object = Aws::S3::Object.new(bucket_name: bucket, key: key, client: client) end def url object.presigned_url :get end def upload(source_path) object.upload_file source_path end end end
104. pdx.rb, 2016-02-02 Learning to Lib Again 104 A few recent uses Extract, Transform, Load (ETL) app
105. pdx.rb, 2016-02-02 Learning to Lib Again 105 Open Source References • https://github.com/chef/supermarket • https://github.com/bbatsov/rubocop & any gem
106. pdx.rb, 2016-02-02 Learning to Lib Again 106 In conclusion Give putting code in lib a try!
107. pdx.rb, 2016-02-02 Learning to Lib Again 107 In conclusion It encourages splitting up code into smaller action classes.
108. pdx.rb, 2016-02-02 Learning to Lib Again 108 In conclusion It feels a lot more like Ruby programming than most other aspects of Rails development.
109. pdx.rb, 2016-02-02 Learning to Lib Again 109 In conclusion The structure and style of code in lib is totally up to the developer, which can feel liberating.
110. pdx.rb, 2016-02-02 Learning to Lib Again 110 In conclusion Also, fast tests!
111. pdx.rb, 2016-02-02 Learning to Lib Again 111 Thank you! Brett Chalupa @brettchalupa http://www.brettchalupa.com