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Rails Antipatterns | Open Session with Chad Pytel

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As developers worldwide have adopted the Ruby on Rails web framework, many have fallen victim to common mistakes that reduce code quality, performance, reliability, stability, scalability, and …

As developers worldwide have adopted the Ruby on Rails web framework, many have fallen victim to common mistakes that reduce code quality, performance, reliability, stability, scalability, and maintainability. Even experienced developers will find that they can reevaluate the work they've done and make it better.
In this session, Chad Pytel will provide an overview of some of these common mistakes as well as take questions from the audience and provide real-world advice. Bring your issues and get expert advice on how to bring your code in line with today's best practices.

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Transcript

  • 1. Our Presentation Will Begin ShortlyRails AntiPatternsWorkshopMay 12, 2011 Matt Reider, Director of Training Engine Yard Chad Pytel, Founder & CEO thoughtbot Inc.
  • 2. Rake Tasks
  • 3. Are you testing them?
  • 4. What makes them hard to test? • Scripts that live outside app • Often have network and file access • Often have output
  • 5. Example Tasknamespace :twitter do task :search => :environment do puts "Searching twitter." Twitter.search("@cpytel").each do |result| puts "Processing #{result.inspect}." alert = Alert.create(:body => result) alert.save_cache_file! end end puts "All done!"end
  • 6. One possible way to test
  • 7. context "rake twitter:search" do setup do # How slow is this going to be? Very. @out = `cd #{Rails.root} && rake twitter:search 2>&1` end
  • 8. should "print a message at the beginning" do assert_match /Searching/i, @outend
  • 9. should "find all tweets containing @cpytel" do # this one would be based entirely on luck.end
  • 10. This Has Problems• Slow• No mocking or stubbing available• Task isn’t in a transaction
  • 11. Basically, no sandboxing
  • 12. How do we fix this?
  • 13. Rake tasks are just Ruby
  • 14. Move it all into the Model
  • 15. class Alert < ActiveRecord::Base def self.create_all_from_twitter_search(output = $stdout) output.puts "Searching twitter." Twitter.search("@cpytel").each do |result| output.puts "Processing #{result.inspect}." alert = create(:body => result) alert.save_cache_file! end output.puts "All done!" end def save_cache_file! # Removes a file from the filesystem. endend
  • 16. The Task is Nice and Skinnynamespace :twitter do task :search => :environment do Alert.create_all_from_twitter_search endend
  • 17. Testing is Pretty Normal# test/unit/alert_test.rbclass AlertTest < ActiveSupport::TestCase context "create_all_from_twitter_search" do setup do # Make sure none of the tests below hit the # network or touch the filesystem. Alert.any_instance.stubs(:save_cache_file!) Twitter.stubs(:search).returns([]) @output = StringIO.new end
  • 18. should "print a message at the beginning" do Alert.create_all_from_twitter_search(@output) assert_match /Searching/i, @output.stringend
  • 19. should "save some cache files" do Twitter.stubs(:search).returns(["one"]) alert = mock("alert") alert.expects(:save_cache_file!) Alert.stubs(:create).returns(alert) Alert.create_all_from_twitter_search(@output)end
  • 20. should "find all tweets containing @cpytel" do Twitter.expects(:search). with("@cpytel"). returns(["body"]) Alert.create_all_from_twitter_search(@output)end
  • 21. We can mock and stub!
  • 22. We can use normal tools!• FakeWeb/WebMock• FileUtils::NoWrite
  • 23. In Summary• You can test drive development of your rake tasks• Rake tasks should live inside a model (or class)
  • 24. Views
  • 25. Know Your Helpers
  • 26. Know How They Change
  • 27. # Edit form<%= form_for :user, :url => user_path(@user), :html => {:method => :put} do |form| %>
  • 28. <%= form_for @user do |form| %>
  • 29. <!-- posts/index.html.erb --><% @posts.each do |post| -%> <h2><%= post.title %></h2> <%= format_content post.body %> <p> <%= link_to Email author, mail_to(post.user.email) %> </p><% end -%>
  • 30. Move the post content into a partial
  • 31. <!-- posts/index.html.erb --><% @posts.each do |post| -%> <%= render :partial => post, :object => :post %><% end -%><!-- posts/_post.erb --><h2><%= post.title %></h2><%= format_content post.body %><p><%= link_to Email author,mail_to(post.user.email) %></p>
  • 32. Looping was built into render
  • 33. <!-- posts/index.html.erb --><%= render :partial => post, :collection => @posts %><!-- posts/_post.erb --><h2><%= post.title %></h2><%= format_content post.body %><p> <%= link_to Email author, mail_to(post.user.email) %></p>
  • 34. <!-- posts/index.html.erb --><%= render :partial => post, :collection => @posts %><!-- posts/_post.erb --><h2><%= post.title %></h2><%= format_content post.body %><p> <%= link_to Email author, mail_to(post.user.email) %></p>
  • 35. <%= render :partial => @posts %>
  • 36. <%= render @posts %>
  • 37. Dynamic Page Titles
  • 38. <!-- layouts/application.html.erb --><head> <title> Acme Widgets : TX-300 Utility Widget </title></head>
  • 39. class PagesController < ApplicationController def show @widget = Widgets.find(params[:id]) @title = @widget.name endend<!-- layouts/application.html.erb --><head> <title>Acme Widgets : <%= @title %></title></head>
  • 40. This is all View
  • 41. There is a Helper
  • 42. <!-- layouts/application.html.erb --><head> <title> Acme Widgets : <%= yield(:title) %> </title></head><!-- widgets/show.html.erb --><% content_for :title, @widget.title %>
  • 43. Default Title
  • 44. <!-- layouts/application.html.erb --><head> <title> Acme Widgets : <%= yield(:title) || "Home" %> </title></head>
  • 45. What else can we use this for?
  • 46. <!-- layouts/application.html.erb --><div class="sidebar"> This is content for the sidebar. <%= link_to "Your Account", account_url %></div><div class="main"> The main content of the page</div>
  • 47. <!-- layouts/application.html.erb --><%= yield(:sidebar) %><div class="main"> The main content of the page</div><!-- layouts/application.html.erb --><% content_for :sidebar do %> <div class="sidebar"> This is content for the sidebar. <%= link_to "Your Account", account_url %> </div><% end %>
  • 48. Avoid Duplication
  • 49. <!-- layouts/application.html.erb --><div class="sidebar"> <%= yield(:sidebar) %></div><div class="main"> The main content of the page</div><!-- layouts/application.html.erb --><% content_for :sidebar do %> This is content for the sidebar. <%= link_to "Your Account", account_url %><% end %>
  • 50. Conditional Sidebar<!-- layouts/application.html.erb --><% if content_for?(:sidebar) -%> <div class="sidebar"> <%= yield(:sidebar) %> </div><% end -%><div class="main"> The main content of the page</div><!-- app/views/products/show.html.erb --><% content_for :sidebar do %> This is content for the sidebar. <%= link_to "Your Account", account_url %><% end %>
  • 51. Upcoming ClassesZero to Rails 3 in four days•May 23-26•VirtualRails AntiPatterns•Best Practices•Boston – June 6 & 7•San Francisco – June 13 & 14 Learn more at: Engineyard.com/university