Ruby on rails, components, ActiveRecord, Routing

1. Ruby on Rails
Mehmet Beydogan
2014

2. Ruby on Rails
Mehmet Beydogan
2014

3. Why Ruby?
“Ruby is natural more than simple”

4. Everything is an object
5.times do
puts “Hello World”
end
Hello World
Hello World
Hello World
Hello World
Hello World
5.class
=> Fixnum=> Fixnum
nil.class
=> NilClass

5. Ruby Blocks
patients.each do |patient|
if patient.ill?
physician.examine patient
else
patient.jump_for_joy!
end
end
You can group a set of instructions together

6. Open Classes
class String
def write_size
self.size
end
end
size_writer = "Tell me my size!"
puts size_writer.write_size
In Ruby, classes are never closed,
you can always add methods to an existing class.

7. Method Missing
class Dummy
def method_missing(m, *args, &block)
puts "There's no method #{m}"
end
end
Dummy.new.anything
method_missing is in part a safety net: It gives you a way to
intercept unanswerable messages and handle them gracefully

8. Method Missing
User.find_by_name
User.find_by_email
You can use regular expressions to more dynamic classes

9. Ruby on Rails

10. Rails
-Convention Over Confuguration
-DRY – Dont Repeat Yourself
-MVC
Princibles

11. Convention Over
Confuguration
Model: User
Table: users
Controller: users_controller

12. MVC

13. REST
-simplifies component implementation
-reduces the complexity of connector semantics,

14. Rails Components
-Active Record
-Database Migrations
-Active Record Validations
-Active Record Callbacks
-Active Record Assocations
Model Layer
-Action View
-Layouts & Partials
-Rendering
View Layer
-Controller Overview
-Routing
Controller Layer

15. Rails Components
-i18n
-Action Mailer
-Asset Pipeline
-Generators
More Components

16. Model Layer

17. Active Record
-Represent models and their data
-Represent associations between these models
-Represent inheritance hierarchies through related models
-Validate models before they get persisted to the database
-Perform database operations in an object-oriented fashion.

18. Creating Active Record
Models

19. Read

20. Update

21. Delete

22. Active Record Migrations
app/db/migrations/create_publications.rb

23. Active Record Migrations
Supported Methods
add_column
add_index
add_reference
add_timestamps
create_table
create_join_table
drop_table
drop_join_table
remove_timestamps
rename_column
rename_index
remove_reference
rename_table

24. Running Migrations

25. Active Record Validations
Validations are used to ensure that only valid data is saved into your database.

26. format

27. length

28. numericality

29. presence

30. uniqueness

31. Validation Errors

32. Active Record Callbacks
-Active Record provides hooks into this object life cycle so
that you can control your application and its data.
-Callbacks allow you to trigger logic before or after an
alteration of an object's state.

33. Callback Registration

34. When does it get triggered?
-Creating an Object
before_validation
after_validation
before_save
around_save
before_create
around_create
after_create
after_save
-Updating an Object
before_validation
after_validation
before_save
around_save
before_update
around_update
after_update
after_save
-Destroying an Object
before_destroy
around_destroy
after_destroy

35. Active Record Associations
They make common operations simpler and easier in your code.
-Get a user's all posts
-Get the author of a post

36. Why Associations?
Consider we have Order and Customer models

37. Why Associations?
Creating an order

38. Why Associations?
Deleting all orders of a customer while deleting a customer

39. IT'S PAINFUL!

40. Use Associations
Creating an order
Deleting a customer with it's orders

41. belongs_to

42. has_one

43. has_many

44. has_and_belongs_to_many

45. has_many through

46. Polymorphic

47. View Layer
-Action View
-Layouts & Partials
-Rendering

48. Action View
-Action View is responsible for compiling the response.
-Action View templates are written using embedded Ruby in tags mingled with HTML.
-All view files must be in app/views folder

49. app/views/posts/index.html.erb
app/views/posts/new.html.erb
app/views/posts/edit.html.erb
app/views/posts/show.html.erb

50. Templates
ERB: Embedded RuBy
list_people.html.erb

51. Partials
To simplify templates

52. Controller Layer
-Controller Overview
-Routing

53. Controller Layer
-Controller is responsible for making sense of the request and producing the
appropriate output
-Rails favors pluralization of the last word in the controller's name
ClientsController
SiteAdminsController
PostsController

55. Routing
-The Rails router recognizes URLs and dispatches them to a controller's action.
-Generate paths and URLs, avoiding the need to hardcode strings in your views.
routes.rb
Request
index.html.erb

56. Where to start?
-http://guides.rubyonrails.org
-http://railscasts.com

57. Questions?