Act as state machine description

2. State diagrams are used to give an abstract description of the behavior of a system. This behavior is analyzed and represented in series of events, that could occur in one or more possible states.

5. include AASM

6. aasm_column :state

7. aasm_initial_state :created

8. aasm_state :created

9. aasm_state :published

10. aasm_state :unpublished

11. aasm_state :deleted

15. article.state # nil

16. article.save # true

17. article.state # "created"

18. article.created? # true

19. article.published? # false

21. article.unpublish!

22. article.delete!

24. The state also comes with a few callbacks that can be used.

25. 1. enter

26. 2.after

27. 3. exit

28. state :published, :enter => :do_publish

30. Using :guard option you can add some sort of validation for a transition.

31. Eg:

32. aasm_event :publish do

33. transitions :to => :published, :from => [:created], :guard => Proc.new { |article| article.valid?}

34. end