Trailblazer: Making Your Rails Applications Manageable

Iowa Ruby Brigade meeting July 2016

Transcript

1. TRAILBLAZER Making Your Rails Applications Manageable
2. DOES YOUR RAILS APP HAVE ANY OF THESE?
3. DOES YOUR RAILS APP HAVE ANY OF THESE? • Callback “hell”
4. DOES YOUR RAILS APP HAVE ANY OF THESE? • Callback “hell” • Nested forms
5. DOES YOUR RAILS APP HAVE ANY OF THESE? • Callback “hell” • Nested forms • Controllers with logic not relating to HTTP
6. DOES YOUR RAILS APP HAVE ANY OF THESE? • Callback “hell” • Nested forms • Controllers with logic not relating to HTTP • Models with logic not relating to persistence
7. DOES YOUR RAILS APP HAVE ANY OF THESE? • Callback “hell” • Nested forms • Controllers with logic not relating to HTTP • Models with logic not relating to persistence • Views with several nested if statements and partials
8. TYPICAL SCENARIO
9. TYPICAL SCENARIO • “Small Project”
10. TYPICAL SCENARIO • “Small Project” • rails g scaffold …
11. TYPICAL SCENARIO • “Small Project” • rails g scaffold … • BUSINESS REQUIREMENTS
12. BUSINESS REQUIREMENTS class User < ActiveRecord::Base before_validation :set_role, on: :create accepts_nested_attributes_for :address, update_only: true, reject_if: :blank? end
13. BUSINESS REQUIREMENTS def create @todo = Todo.find(params[:todo_id]) @recording = @todo.build_recording(recording_params) authorize @recording if @recording.save if @recording.reason != 'Not a weight challenge' if @recording.reason == 'Success' flash.now[:notice] = 'Success: Congrats!' else flash.now[:error] = "You were not awarded credits! Reason: #{@recording.reason}" end render :show else render json: ErrorValue.new(@recording), status: :unprocessable_entity end end end
16. SINGLE RESPONSIBILITY PRINCIPLE
17. MODEL: DATABASE PERSISTENCE
18. CONTROLLER: HTTP
19. VIEW: MARKUP/JSON
20. • Forms/Validations? • Actions (CRUD)? • Policies? • View logic? • Callbacks?
21. TRAILBLAZER • “A High-level Architecture For The Web” • A collection of framework-agnostic gems that give your app: Structure Encapsulation Inheritance
22. TRAILBLAZER ARCHITECTURE Request Flow http://trailblazer.to/images/diagrams/stack.png
23. CONTROLLER • Acts as an HTTP endpoint for an operation
24. CONTROLLER class PostsController < ApplicationController def create Post::Create.(...) end ...
25. OPERATION • Acts as an orchestrator of objects that contain the business logic • “creating a comment”, “updating a user” • Composable
26. OPERATION class PostsController < ApplicationController def create run Post::Create do |op| return redirect_to posts_path end render :edit end Equivalent to: op = Post::Create.call(params)
27. OPERATION class Post < ActiveRecord::Base # namespace class Create < Trailblazer::Operation def process(params) puts params end end end
28. FORM • AKA contract • Property: strong parameters • Validation: ActiveModel validations (or dry-validation)
29. FORM class Post < ActiveRecord::Base class Create < Trailblazer::Operation contract do property :title property :body validates :title, length: { minimum: 4 } validates :body, presence: true end def process(params) validate(params[:post]) do contract.save end end end end
30. POLICY • Whether or not you can perform this operation • If not, throws Trailblazer::NotAuthorizedError
31. POLICY class Post::Policy def initialize(user, model) @user, @model = user, model end def create? @user.admin == true end end class Post < ActiveRecord::Base class Create < Trailblazer::Operation include Trailblazer::Operation::Policy policy Post::Policy, :create? contract do ... end def process(params) ... end end end
32. POLICY class PostsController < ApplicationController def create run Post::Create, params: params.merge(current_user: current_user) do |op| class PostsController < ApplicationController before_action :add_user_to_params … private def add_user_to_params params[:current_user] = current_user end end
33. MODEL • Very simple setup
34. MODEL class Post < ActiveRecord::Base class Create < Trailblazer::Operation include Model model Post, :create # or :find or :update def process(params) validate(params[:post]) do contract.save end end end end • :create calls Post.new • :update is the same as :find, they call Post.find(params[:id])
35. MODEL class Post < ActiveRecord::Base class Update < Trailblazer::Operation include Model model Post, :update def process(params) validate(params[:post]) do contract.save end end private def update_model!(params) model_class.find_by(slug: params[:slug]) end end end
36. CELLS • View models • Separate templates and view logic • Reusable components
37. CELLS class Post < ActiveRecord::Base module Cell class Show < Trailblazer::Cell property :title property :body private def author model.author || AnonymousAuthor.new end def full_name "#{author.first_name} #{author.last_name}" end end end end
38. CELLS <article> <header> <h1><%= title %></h1> <p>Published: <%= published_at %></p> </header> <p><%= body %></p> <footer> <p><small>By: <%= full_name %></small></p> </footer> </article>
39. CELLS <div class="container"> <%= cell(Post::Cell::Show, @post) %> </div>
40. DIRECTORY LAYOUT app ├── concepts │ ├── comment │ │ ├── contract │ │ │ ├── create.rb │ │ │ └── update.rb │ │ ├── cell │ │ │ └── new.rb │ │ ├── operation │ │ │ ├── create.rb │ │ │ └── update.rb │ │ └── view │ │ ├── new.erb │ │ └── show.erb
41. REFERENCES • Trailblazer by Nick Sutterer • trailblazer.to • github.com/trailblazer • github.com/apotonick/gemgem-trbrb