Tropical On Rails 2026 — Generators are APIs: Designing Better DX in Rails

Slides reg my talk at Tropical On Rails 2026 in Sao Paulo, Brazil.

Transcript

1. $ rails g talk generators_are_apis \ --at=tropical_on_rails \ --speaker=rpaweb Running via spring preloader in process 12345 invoke rails insert event: Tropical-On-Rails insert schedule: 2026-04-10 insert location: São-Paulo status confirmed create generators_are_apis.live create talks/tor26/slides.html.erb Talk successfully generated. Ready to run at Tropical On Rails.
2. Generators are APIs Designing Better DX in Rails Rafael Peña-Azar · Tropical On Rails 2026 @rpaweb rpaweb.github.io
11. rails generate Tropical On Rails 2026
12. rails g model controller scaffold Tropical On Rails 2026
13. rails g talk:tor26 Tropical On Rails 2026
14. WRITING MY FIRST CUSTOM GENERATOR
15. REWRITE
16. Generator rails g model User \ name:string \ email:string \ --timestamps API call POST /api/users body: { name: string, email: string } Tropical On Rails 2026
17. ❏ Act I — We’ve been thinking about this wrong. ❏ Act II — What bad DX looks like. ❏ Act III — What good DX looks like. ❏ Act IV — The bigger picture. We’re gonna go through 4 acts. Tropical On Rails 2026
18. ❏ Act I — We’ve been thinking about this wrong. ❏ Act II — What bad DX looks like. ❏ Act III — What good DX looks like. ❏ Act IV — The bigger picture. We’re gonna go through 4 acts. Tropical On Rails 2026
19. HOW WE TREAT THEM Input a name → get some files → move on WHAT THEY ACTUALLY ARE The first point of contact between a developer and your architecture Tropical On Rails 2026
20. rails g model User Tropical On Rails 2026
21. Generators are how your architecture propagates Tropical On Rails 2026
22. What we expect from a good API Clear Predictable Consistent Useful ✅ ✅ ✅ ✅ Confusing Unpredictable Unrelated Useless ❌ ❌ ❌ ❌ Naming Inputs Outputs Errors Tropical On Rails 2026
23. Why we tolerate the same problems in our generators? Tropical On Rails 2026
24. API concept Generator equivalent Endpoint name Generator name Request params Arguments & flags Response body Generated files Error messages Failure output Same interface. Different medium. Tropical On Rails 2026
25. A generator IS an API Tropical On Rails 2026
26. ❏ Act I — We’ve been thinking about this wrong. ❏ Act II — What bad DX looks like. ❏ Act III — What good DX looks like. ❏ Act IV — The bigger picture. Acts we’re following on this talk. Tropical On Rails 2026
27. Let's look at some bad APIs. ...I mean generators. Tropical On Rails 2026 ❌
28. Problem 1: Ambiguity $ rails g jet_ui:eject Button $ rails g jet_ui:eject button $ rails g jet_ui:eject btn Tropical On Rails 2026
29. Problem 2: Silence. $ rails g jet_ui:eject btn create app/components/jet_ui/btn_component.rb Tropical On Rails 2026
30. A good API tells you what happened Tropical On Rails 2026
31. Problem 3: No options. No control. $ rails g jet_ui:eject btn create app/components/jet_ui/btn_component.rb create app/assets/stylesheets/jet_ui/btn.css create test/components/jet_ui/btn_component_test.rb create test/components/previews/jet_ui/btn_component_preview.rb # No --no-test. No --no-preview. No flags at all. # The generator decided for you. Tropical On Rails 2026
32. The pattern isn’t the problem. The design is. Tropical On Rails 2026
33. Raise your hand if you've been burned by something like this. Tropical On Rails 2026
34. You just described a BAD API. You just didn’t call it that way. Tropical On Rails 2026
35. ❏ Act I — We’ve been thinking about this wrong. ❏ Act II — What bad DX looks like. ❏ Act III — What good DX looks like. ❏ Act IV — The bigger picture. Acts we’re following on this talk. Tropical On Rails 2026
36. rails g jet_ui:eject Button rails g jet_ui:eject button rails g jet_ui:eject btn rails g jet_ui:eject btn card # Documented convention: # use the component short name. The name should tell you exactly what you'll get. Before. After. Principle 1. Naming is a contract. Tropical On Rails 2026
37. Principle 2. Predictable inputs. class JetUi::EjectGenerator < Rails::Generators::Base desc "Ejects JetUi components into your app for local customisation." argument :components, type: :array, banner: “component [component …]”, desc: “Component(s) to eject (e.g. btn card)” def eject_components components.map(&:downcase).each do |name| MANIFEST[name][:files].each do |entry| template entry[:src], entry[:dest] end end end end Tropical On Rails 2026
38. Principle 3. Tell people what you did and why. class JetUi::EjectGenerator < Rails::Generators::Base # rest of the generator logic here def eject_components components.each do |component| say "Ejecting #{component}..." # logic for generating files say " #{component} ejected.", :green end end def print_next_steps say "Done! Ejected: #{components.join(', ')}", :green say "Run your tests: bundle exec rake test", :cyan end end
39. Principle 3. Tell people what you did and why. $ rails g jet_ui:eject btn Ejecting btn... create app/components/jet_ui/btn_component.rb create app/assets/stylesheets/jet_ui/btn.css btn ejected. Done! Ejected: btn Run your tests: bundle exec rake test
40. $ rails g jet_ui:eject buton create app/components/jet_ui/ Buton_component.rb # Silently creates files for # a component that does not exist. $ rails g jet_ui:eject buton error Unknown component: buton Available: btn, card, modal, alert, badge Did you mean? btn Example: rails g jet_ui:eject btn card Before. After. Principle 4. Errors should tell how to fix them.
41. Principle 5. Design for extension, not rewriting. class JetUi::EjectWithStorybookGenerator < JetUi::EjectGenerator desc "Like jet_ui:eject, but also generates Storybook stories." def generate_stories components.each do |component| template "story.js.tt", "stories/jet_ui/#{component}_component.stories.js" end end end Tropical On Rails 2026
42. ❏ Act I — We’ve been thinking about this wrong. ❏ Act II — What bad DX looks like. ❏ Act III — What good DX looks like. ❏ Act IV — The bigger picture. Acts we’re following on this talk. Tropical On Rails 2026
43. Generators aren't about code. They're about decisions. Tropical On Rails 2026
44. $ rails g jet_ui:eject btn ▼ dev 1 same structure dev 2 same structure dev 3 same structure dev 4 same structure Tropical On Rails 2026
45. "The best generators are the ones you never have to explain. The code they produce speaks for itself — because you designed the conversation." Tropical On Rails 2026
46. $ rails g talk generators_are_apis \ --at=tropical_on_rails \ --speaker=rpaweb Running via spring preloader in process 12345 invoke rails insert event: Tropical-On-Rails insert schedule: 2026-04-10 insert location: São-Paulo status confirmed create generators_are_apis.live create talks/tor26/slides.html.erb Talk successfully generated. Ready to run at Tropical On Rails.
47. Generators are small tools Tropical On Rails 2026
48. But small tools used daily, shape entire systems! Tropical On Rails 2026
49. Design them like it matters. Because it does! @rpaweb Tropical On Rails 2026
50. ❏ Act I — We’ve been thinking about this wrong. ❏ Act II — What bad DX looks like. ❏ Act III — What good DX looks like. ❏ Act IV — The bigger picture. We covered all acts! Tropical On Rails 2026
52. I want to show you something I’ve been working on Tropical On Rails 2026
53. rails new Tropical On Rails 2026
54. mix phx.new laravel new Tropical On Rails 2026
58. $ pragon create my_new_rails_app \ --framework=rails $ pragon create my_new_php_app \ --framework=laravel $ pragon create my_new_phx_app \ --framework=phoenix $ pragon add stripe $ pragon remove search $ pragon run:migrations $ pragon run:deployment CORE FATE
59. That wasn’t the best part at all Tropical On Rails 2026
60. Tropical On Rails 2026
62. https://pragon.build Tropical On Rails 2026
63. Thank you! Rafael Peña-Azar · Tropical On Rails 2026 @rpaweb rpaweb.github.io