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RoR 101: Session 3
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RoR 101: Session 3


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Part 3 of 6

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  • 1. Building Web Apps with Rails III
  • 2. Recap● Rails Console● ActiveRecord Queries● Views ● Embedded Ruby Syntax ● Layouts ● Helper Methods
  • 3. Recap: ActiveRecord Models Controllers DB In stations_controller.rb (show):@stations = Station.find(params[:id])
  • 4. The Rails Console1. Open the terminal2. Navigate to the firstfm directory3. Run the commands: rails console @stations = Station.all
  • 5. show.html.erb:<%= link_to Edit, edit_station_path(@station) %> |<%= link_to Back, stations_path %> These are both view helpers.
  • 6. <!DOCTYPE html><html><head> <title>Firstfm</title> <%= stylesheet_link_tag "application" %> <%= javascript_include_tag "application"%> <%= csrf_meta_tags %></head><body><%= yield %> The default layout template.</body></html>
  • 7. Web BrowserSession 3 Rails Routing System Views ModelsDB Controllers
  • 8. Web BrowserSession 3: Routing Rails Routing System Views ModelsDB Controllers
  • 9. Web BrowserSession 3:Validations & Testing Rails Routing System Views ModelsDB Controllers
  • 10. Web BrowserSession 3:Associations& The Stream Model Rails Routing System Views Models DB Controllers
  • 11. Routing in Rails
  • 12. Routing in Rails ● Which controller to Web Browser instantiate ● Which action to invoke Parameter(s) to pass ? ●
  • 13. Routing in Rails Web Browser ● Follows routing rules defined in: Routing System ● config/routes.rb Views Controllers
  • 14. Routing in RailsConfig/Routes.rb:Firstfm::Application.routes.draw do resources :stations #commentsend Generates RESTful routes for the Station resource
  • 15. Routing in RailsConfig/Routes.rb:Firstfm::Application.routes.draw do resources :stationsTransfer Principles: Representational State #comments Use HTTP methods explicitlyend Be stateless Expose directory structure-like URIs Handle multiple formats e.g. XML, JSON
  • 16. Routing in RailsConfig/Routes.rb:Firstfm::Application.routes.draw do resources :stations #commentsend This means we can accept requests for all the CRUD actions
  • 17. Routing in Rails: Terminal Time!1. Open the terminal2. Navigate to the firstfm directory3. Run the commands: rake routes
  • 18. Routing in Rails: Writing RulesConfig/Routes.rb: resources :stations
  • 19. Routing in Rails: Writing RulesConfig/Routes.rb (rewritten):get statations => stations#indexget statations/:id => stations#showget statations/new => stations#newpost statations => stations#createput statations/:id => stations#updatedelete statations/:id =>stations#destroy
  • 20. Routing in Rails: Writing RulesConfig/Routes.rb: resources :stationsGenerates URL helpers for us e.g. stations_path station_path(:id) new_station_path Etc...
  • 21. Routing in Rails: Task1. Define a root controller and action2. Add a new action 2.1 Write a new method in the controller 2.2 Write a view file for it 2.3 Write a routing rule so we can access it For docs on routing:
  • 22. Tests and Validations
  • 23. We have aproblem...
  • 24. Our app acceptsempty station data
  • 25. Tests and ValidationsSolution: Write validations to prevent erroneous data
  • 26. Tests and ValidationsBut First! Lets write tests.
  • 27. Tests and Validations Scaffolding has generated test files for us
  • 28. Tests and Validations: Unit TestingIn firstfm/test/unit/station_test.rb:require test_helperclass StationTest < ActiveSupport::TestCase  # test "the truth" do  #   assert true  # endend We write tests by writing out assertions
  • 29. Tests and Validations: Unit Testingrequire test_helperclass StationTest < ActiveSupport::TestCase  test "the truth" do     assert 10 > 9  endendassertions evaluate whether an object is what we expect it to be
  • 30. Tests and Validations: Unit TestingRunning test scriptsruby -Itest <script_name>e.g.ruby -Itest test/unit/station_test.rb
  • 31. Tests and Validations: Unit Testingruby -Itest test/unit/station_test.rbScript report example:pass: 1, fail: 1, error: 0total: 2 tests with 2 assertions in 0.215168805seconds
  • 32. Tests and Validations: Unit Testingtest "shouldnt save without name" do station = station.url = “” station.description = “A cool radio station” assert !station.saveend
  • 33. Tests and Validations: Unit Testingtest "should save" do station = = “My Radio” station.url = “” station.description = “A cool radio station” assert station.saveend
  • 34. Tests and Validations: Task!Write test cases for your validationsConsider more than just presence of data e.g.● Name shouldnt be longer than x characters● URL should start with http://● Description shouldnt be less than x characters
  • 35. Tests and Validations: Validate● We write validation code in the model● Rails provides us with several built in validation methods● For example: validates_presence_of
  • 36. Tests and Validations: Validate Example: Using validates_presence_of In models/station.rb:class Station < ActiveRecord::Base validates_presence_of :name, :url,:descriptionend
  • 37. Tests and Validations: Task! Make your tests pass by implementing validations like belowclass Station < ActiveRecord::Base validates_presence_of :name, :url,:descriptionend
  • 38. Associations in RoRAdding Streams
  • 39. First FM Station
  • 40. First FM Station Stream
  • 41. First FM Station Has many Streams
  • 42. First FMLets generate the stream model rails generate model stream url:string name:stringCreate the db table by running the migration script... rake db:migrate
  • 43. First FMLets check out our new stream modelrails cmystream =
  • 44. First FM Station Stream
  • 45. First FM Station Has many Streams
  • 46. First FMhas_many :streams Station Has many Streams belongs_to :station
  • 47. First FMLets see if our models are associated rails c mystation = Station.first mystation.streams
  • 48. First FM OH NOES! We need to add a secondary key.rails generate migration AddStationIdToStreams station_id:integer
  • 49. First FM OH YEA! Weve got a secondary key!rake db:migraterails cmystation = Station.firstmystation.streams
  • 50. First FM Build Build and save a new streamstream =