The document discusses using decorators and presenters in Ruby on Rails to keep views tidy and move logic out of the views. Decorators and presenters both act as wrappers around models to help with presentation. Decorators can add additional responsibilities to objects dynamically, while presenters maintain object-oriented logic in the views. The draper gem facilitates using the decorator pattern in Rails apps.

1. Decorator Decorator
& &
PresenterPresenter
By: Carlos Sánchez Pérez madrid­rbBy: Carlos Sánchez Pérez madrid­rb
Tidy VIEWSTidy VIEWS

2. WHO AM I?
Person.new(
NameName : 'Carlos Sánchez Pérez',
LoveLove : 'Web Dev ­ Ruby & Rails',
TwitterTwitter : '@carlossanchezp',
JobJob : 'ASPgems',
GithubGithub : 'carlossanchezp',
Blog Blog ::'carlossanchezperez.wordpress.com
'
)
Let me show you about my ideas, in my blog.
I'll be there for you tomorrow....

3. The Problem

4. VIEWS: Responsibility Overload

5. FAT MODEL

6. BIGGEST HELPERS

7. What's wrong with it?

9. app/views/users/show.html.erb

10. DECORATOR PRESENTER

11. PRESENTERS Pattern
Tidy Views

12. The idea of a Presenter was first introduced
to the Rails community by Jay Fields in a
series of blog articles in 2006 and 2007.
Rails Presenter Pattern Jay Fields
Wikipedia:Model–view–presenter

13. PRESENTER
● Presenters are also decorators.
● The presenters is their
proximity to the view and live
very close to the view layer.
● In fact, they are meant to be a
representation of the delegate
object within the view.
● The main goal of presenters is
to keep logic out of the view.
● Presenters maintain an object­
oriented approach to logic in
the view.

14. MODEL
VIEW
My name is Presenter,
Can I help you?
This way, presenters act like decorators.
Wrap a Rails model and aid in the presentation.

19. app/views/users/show.html.rb

20. DECORATOR Pattern
Tidy Views

21. DECORATOR
● Start needing logic in the view
or start thinking about a helper
method, you can implement a
method on the decorator instead.
● Attach additional
responsibilities to an object
dynamically.
● A decorator changes an object's
skin.

22. Jeff Casimir's draper is a gem that embodies
the pattern and also allows you to invoke
Rails' view helpers by exposing the view
context in your decorators.

23. CHANGE: UserDecorator.find(params[:id]

25. App/views/users/show.html.erb

26. DECORATOR PRESENTER
PRESENTER
DECORATOR

27. How to share?
In a view with decorator
and without decorator

30. DRAPPER
def helpers
Draper::ViewContext.current
end
alias_method :h, :helpers

32. Is there anything else?

33. Decorator
OTHER SIDE
Sending Notifications Using
Decorators

34. CALLBACK
MODEL
SEND

36. “Single Responsibility Principle”
MODEL
FIND USER
DECORATOR
CALLING METHOD
DECORATOR

37. One more
Notifications

41. The same object diferent Render

42. Exhibit Pattern

43. EXHIBIT
● Exhibits are just decorators.
● Add some additional
functionality.
● The additional functionality
added will extend, but not
disrupt.
● Introducing the Exhibit Pattern
by Avdi Grimm in his book “Objects
on Rails“.

46. Conclusion

47. The power of decorators

48. LINKS
Decorator gem: Decorator gem: https://github.com/drapergem/draperhttps://github.com/drapergem/draper
Objects In Rails Objects In Rails http://objectsonrails.com/http://objectsonrails.com/
http://blog.jayfields.com/2007/03/rails­presenter­pattern.htmlhttp://blog.jayfields.com/2007/03/rails­presenter­pattern.html
http://railscasts.com/episodes/286­draperhttp://railscasts.com/episodes/286­draper

49. Any questions?

50. Dedication to....

51. Thanks ASPgems and twitter people!!
THANKS A LOT!!

52. That's all folks!!
and
Thanks a lot for
your attention