Rails Magazine - Issue 3

30
Ruby Web Frameworks: A Dive into Waves by Carlo Pecchia
30
So, let’s generate a resource for items:
## resources/item.rb
module TodoManager
module Resources
class Item < Default
end
end
end
# ‘GET /items’
on(:get, [‘items’]) do
items = controller.all
view.list(:items => items)
end
and keep resources/map.rb smaller:
## resources/map.rb
module TodoManager
module Resources
class Map
include Waves::Resources::Mixin
# redirect ‘/’ request do ‘/items’
on ( :get, [] ) { redirect ‘/items’ }
# delegate to item resource any path
like ‘/items’
on (true, [“items”]) { to :item }
# delegate to item resource any path
like ‘/items/’
on (true, [“items”, true]) { to :item }
end
end
end
Hitting the refresh button on our browser shows us that
everything works as expected.
Now we can inject the full REST behaviour to our “item”
resource.
Let’s add the handling for GET /items/ in resources/item.
rb:
# ‘GET /items/’
on(:get, [‘items’, :name]) do
item = controller.find(captured.name)
view.show(:item => item)
end
And see how it is rendered in our browser:
So it’s easy to continue defining all the other “REST methods”
(exercise for the readers!). Don’t forget that the PUT and
DELETE methods are not currently supported by the browsers,
so one of the best way is to mimic them with POST and some
hidden parameters (that is the way it is done in Rails, for
instance).
Basically here we can see how routing works. A path is
defined as an array of “chunks”:
# /items/past/1234
[ “items”, “past”, {:name => /\d+/} ]
# /items/some-slug-here/and_something_else
[ “items”, “past”, :name ]
Conclusion
As promised before, we’d like to shortly show how the DSL
for defining routes work. Well, it’s based on the concept of
“Functor”:
fib = Functor.new do
given( 0 ) { 1 }
given( 1 ) { 1 }
given( Integer ) do |n|
self.call( n-1 ) + self.call( n-2 )
end
end
So we can easily create a “request functor”, that is a functor
defined on a resource class to match a given request pattern.
So, for example:
class Item
include Waves::Resources::Mixin
on( :get, [‘name’] ) { “default item
here” }
end