Brief introduction to the Rails idiom enabled by the decent_explosure gem.

1. decent_exposure
@mattyoho
yoho@hashrocket.com

2. Hashrocket Chicago is hiring.

3. Join us.

4. @voxdolo/Stephen Caudill

5. http://github.com/voxdolo/decent_exposure

6. idiom

7. finder calls everywhere

8. instance variables in views

9. @yuck

10. gem install decent_exposure

11. rspec’s let

12. context "validation" do
let(:post) { Factory.build(:post) }
it "requires a poster" do
post.poster = nil
post.should_not be_valid
post.errors.on(:poster).should be_present
end
end

13. resource_controller abuse

14. class FooController < AppController
def show
@foo = Foo.find(params[:id])
end
end

15. class FooController < AppController
expose :foo
def show
end
end

16. Foo.find(params[:foo_id] || params[:id])

17. class FooController < AppController
expose(:foo) { user.foos.first }
def show
end
end

18. memoization

19. memorization

20. memoization

21. def widget
@widget ||= Widget.find(123)
end

22. hide_action/helper_method

23. custom default

24. class MyFooController < AppController
default_exposure do
Foo.for_user(current_user)find
end
end

25. the code

26. module DecentExposure
def inherited(klass)
closured_exposure = default_exposure
klass.class_eval do
default_exposure(&closured_exposure)
end
super
end
attr_accessor :_default_exposure
def default_exposure(&block)
self._default_exposure = block if block_given?
_default_exposure
end
def expose(name, &block)
closured_exposure = default_exposure
define_method name do
@_resources ||= {}
@_resources[name] ||= if block_given?
instance_eval(&block)
else
instance_exec(name, &closured_exposure)
end
end
helper_method name
hide_action name
end
alias let expose
end

27. attr_accessor :_default_exposure
def default_exposure(&block)
self._default_exposure = block if block_given?
_default_exposure
end

28. def inherited(klass)
closured_exposure = default_exposure
klass.class_eval do
default_exposure(&closured_exposure)
end
super
end

29. def expose(name, &block)
closured_exposure = default_exposure
define_method name do
@_resources ||= {}
@_resources[name] ||= if block_given?
instance_eval(&block)
else
instance_exec(name, &closured_exposure)
end
end
helper_method name
hide_action name
end
alias let expose

30. instance_eval/instance_exec

31. foo.instance_eval(&block)

32. self = foo

33. Trivia!

34. views

35. app/views/posts/post.html.erb
<p>
<b>Poster:</b>
<%= post.poster_id %>
</p>
<p>
<b>Title:</b>
<%=h post.title %>
</p>
<p>
<b>Origin:</b>
<%=h post.origin %>
</p>
<p>
<b>Message:</b>
<%=h post.message %>
</p>

36. class PostsController < AppController
expose(:post) { Post.first }
def show
render :template => ‘posts/post’
end
end

37. app/views/posts/post.html.erb
<p>
<b>Poster:</b>
<%= post.poster_id %>
</p>
<p>
<b>Title:</b>
<%=h post.title %>
</p>
<p>
<b>Origin:</b>
<%=h post.origin %>
</p>
<p>
<b>Message:</b>
<%=h post.message %>
</p>

38. app/views/posts/post.html.erb
<p>
<b>Poster:</b>
<%= post.poster_id %>
</p>
<p>
<b>Title:</b>
<%=h post.title %>
</p>
helper_method
<p>
<b>Origin:</b>
<%=h post.origin %>
</p>
<p>
<b>Message:</b>
<%=h post.message %>
</p>

39. app/views/posts/post.html.erb
<p>
<b>Poster:</b>
<%= post.poster_id %>
</p>
<p>
<b>Title:</b>
<%=h post.title %>
</p>
How many block invocations?
<p>
<b>Origin:</b>
<%=h post.origin %>
</p>
<p>
<b>Message:</b>
<%=h post.message %>
</p>

40. What about exceptions?

41. class PostsController < AppController
expose(:post) do
Foo.find(params[:id])
end
end

42. class PostsController < AppController
expose(:post) do
Foo.find_by_id(params[:id])
end
end

43. class PostsController < AppController
expose(:post) do
begin
rescue => e
end
end
end

44. rescue_from ActiveRecord::RecordNotFound, :with => :omg_wtf

45. working with Rails

46. ActionController::Base.class_eval do
extend DecentExposure
superclass_delegating_accessor :_default_exposure
default_exposure do |name|
model_class = name.to_s.classify.constantize
model_class.find(params["#{name}_id"] || params['id'])
end
end

47. testing

48. assigns[:posts]

49. assigns[:posts]

50. testing

51. integration testing

53. Questions?
yoho@hashrocket.com