Mountable Engines - Lonestar Ruby 2012

An indepth look at how to create and design Engines for Rails, to take advantage of the reusable and modular nature of the framework.

Transcript

1. Mountable Engines Playing well with other apps Patrick Peak @peakpg
2. About Me
3. The Problem: Reuse is hard
4. Duplication is the root of all evil.
5. Start with a Library
6. Plugins
7. Generated code makes upgrades costly
8. Agenda • Why I care about Engines • What are they? • Building one • Learning to configure • Making installation easy • Using the Asset Pipeline • Working with other Engines
9. Evolution of a CMS 2.3 3.0 Engines Introduced 3.1 Mountable Initializers Asset Pipeline 3.2
10. What are Engines? Responsibilities: •  Business Domain •  Selling Stuff •  Managing Users •  Blogging App #2
11. Separation of Concerns Selling Stuff Managing Users Blogging Business Domain App #2
12. Examples Popular Engines
13. E-commerce
14. Authentication
15. Admin Dashboards
16. Building an Engine
17. What the world needs… $ rails plugin new another --mountable
18. Result: A Gem with a Rails App inside Rails App Gem
19. Add a Resource $ rails g resource Page name path content
20. ‘Typical’ Controller
21. Isolated Controller
22. Isolated Namespace
23. Routing Engines own their Routes
24. Engine Routes Rails.application.routes.draw
25. Our Awesome UI
26. Mounting the Engine App Root
27. Route Helpers <%= main_app.root_url %> # => / <%= another.root_url %> # => /another <%= another.page_path(@page) %> # => /another/pages/1
28. Get Smarter
29. Inside the Engine
30. In your App
31. Department of Redundancy Department…
32. Migrations Sharing Structure across Projects
33. Namespaced Tables
34. From Gem to Project $ rake another:install:migrations • Copies all files from db/migrate into a project • Won’t overwrite • Retimestamps
35. After installing 2 1
36. For multiple engines $ rake railties:install:migrations
37. Configuratin’ Provide Reasonable Defaults
38. http://edgeguides.rubyonrails.org/configuring.html
39. Initializers
40. Adding behavior to Rails
41. Middleware Stack
42. “Suggested” Generators
43. Make your engine configurable
44. Be Nice Make life easy for new users
45. Write a Readme gem "another" $ bundle install $ rake another:install:migrations $ rake db:migrate mount Another::Engine => "/another"
46. Improve Installation gem "another” $ rail g another:install
47. Generators
48. Asset Pipeline Packaging the view
49. Before /public $ rake copy:assets
50. After Project gem "ckeditor_rails", "3.6.2.2"
51. My Favorite Key
52. Working Together Ups and Downs of multiple engines
53. Common stacks are ok My Site BrowerCMS News Blog
54. Conventions $ rails g cms:install bcms_news
55. Common Installer
56. The vision Your Engine Rails Admin
57. Challenges A. Incompatible dependencies B. Rails has no common security model C. Mismatched user interfaces
58. A. Incompatible Dependencies Devise =2.1.1 ~>2.0.0
59. Solving Dependencies • Minimize dependencies • Follow rational versioning policy: o  Rubygems ‘recommended’ o  Major.Minor.Build (i.e. 3.5.4) §  Major – Backwards incompatible §  Minor – Backwards compatible, new features §  Build – Backwards compatible, details • Robustness Principle – Be liberal in what you accept o  ~> 2.0 better than ~>2.0.0
60. B. No common security model Your App Restful Auth Devise current_user?
61. Authentication Who are you, really?
62. Authorization Are you allowed to do that?
63. I don’t care, just pick something…
64. C. Mismatched UIs
65. Recap What I hope you learned
66. Engines are the Future, and Awesome.
67. Reduce errors from duplication
68. When done right…
69. The End Thanks! Feedback? @peakpg
70. Attributions http://dilbert.com/strips/comic/2009-12-03/ http://trevorlibrarian.wordpress.com/2012/04/04/safety-first/ http://www.flickr.com/photos/rosenfeldmedia/4459977458/sizes/o/in/photostream/ https://www.ruby-toolbox.com/ http://www.flickr.com/photos/7571290@N05/440978769/sizes/m/in/photostream/ http://www.spreecommerce.com http://www.flickr.com/photos/verseguru/168920451/sizes/o/in/photostream/ http://www.flickr.com/photos/richardgiles/5284155911/sizes/o/in/photostream/ http://www.flickr.com/photos/museemccordmuseum/2918567169/sizes/o/in/photostream/ http://www.flickr.com/photos/whisperwolf/4487007569/