The document discusses routing in Merb, including: - Setting up simple routes that map URLs to controllers and actions - Defining routes that accept variable path segments - Adding conditions and optional path segments to routes - Handling subdomain routing - Generating URLs from routes - Creating default, resourceful, and nested routes - Using friendly URLs and redirecting legacy URLs - Checking authentication in routes

2. Bryan Ray
http://bryanray.net

3. The Merb Router
In Depth ...
Code Repository
https://github.com/merbday/atlanta
http://github.com/merbday/atlanta/tree/master/router

4. Thanks
Carl Lerche
Anyone else who has contributed to Merb ...

5. Simple Routes
Merb::Router.prepare do
# resources :articles
# RESTful routes
# resources :posts
end

6. Match 3 simple route
Merb::Router.prepare do
match(quot;/signupquot;).
to(:controller => quot;usersquot;, :action => quot;newquot;).
name(:signup)
end
Generating the route:
url(:signup) => /signup

7. Routes with variables
Merb::Router.prepare do
match(quot;/articles/:year/:month/:day/:titlequot;).
to(:controller => quot;articlesquot;, :action => quot;showquot;).
name(:article)
end

8. Routes with variables
Generating
url(:article, :year => 2008, :month => 07, :day => 22,
:title => quot;Awesomenessquot;)
# => /articles/2008/07/22/Awesomeness

9. Optional Path Segments
match('/articles(/:year(/:month(/:day)))/:title').
to(
:controller => :articles,
:action => quot;with_optional_segmentsquot;).
name(:articles)
/articles/hello # => { :title => “hello” }
/articles/2008/12/hello
# => { :title => “hello”, :year => “2008”,
:month => “12” }

10. Routes with conditions
match(quot;/articlesquot;) do
with(:controller => quot;articlesquot;) do
match(quot;/:titlequot;, :title => /[a-z]+$/).
to(:action => quot;with_titlequot;)
match(quot;/:idquot;, :id => /^[d]+$/).to(:action => quot;with_idquot;)
end
end
/articles/hello # => Renders the #with_title action
/articles/12 # => Renders the #with_id action

11. The Subdomain Problem
The end goal
http://<account>.localhost:4000
http://bryan.localhost:4000
Matching inside the router
match(:account => 'bryan').
to(:controller => 'articles', :action => 'with_account')

12. The Subdomain Problem
module Merb
class Request
def account
subdomains(0).first
end
end
end

13. #url generation ...
url(:articles, :title => 'hello')
# => /articles/hello
url(:articles, :year => 2008, :title => 'hello')
# => /articles/2008/hello
url(:articles, :year => 2008, :month => 12, :title => 'hello')
# => /articles/2008/12/hello
url(:articles, :year => 2008, :month => 12, :day => 07, :title =>
'hello')
# => /articles/2008/12/7/hello
# Anonymous Parameters
url(:articles, 2008, 12, 07, :title => 'hello')
# => /articles/2008/12/7/testing

14. Default Routes
def default_routes(params = {}, &block)
match(quot;/:controller(/:action(/:id))(.:format)quot;).
to(params, &block).name(:default)
end

15. Resource-ful Routes
Merb::Router.prepare do
# Resource-ful Routes
resources :articles
end
/articles GET => index
/articles POST => create
/articles/new GET => new
/articles/:id GET => show
/articles/:id PUT => update
/articles/:id DELETE => destroy
/articles/:id/edit GET => edit
/articles/:id/delete GET => delete

16. Nested Routes
resources :articles
resources :comments
end
Generating
link_to quot;Article Commentsquot;, url(:article_comments, 1)
# => /articles/1/comments

17. Multiple Nested Routes
resources :articles do
resources :comments
end
resources :songs do
resources :comments
end
resources :photos do
resources :comments
end

18. Generating the routes...
link_to quot;view commentquot;,
comment.commentable.is_a?(Article) ? url(:article_comment,
comment.commentable.id, comment.id) :
comment.commentable.is_a?(Song) ? url(:song_comment,
comment.commentable.id, comment.id) : url(:photo_comment,
comment.commentable.id, comment.id)

19. Yea, right ...
link_to quot;View Commentquot;, resource(comment.commentable, comment)
Much cleaner ...

20. More Resource examples
resource(@user)
vs.
url(:user, user)
resource(@user, :comments)
vs.
url(:user_comments, user)
resource(@user, @comment)
vs.
url(:user_comment, user, comment)

21. Friendly URLs
Route
resources :users, :identify => :name
Generating
resource(@user) # => /users/bryan

22. Can also use a block
identify(Article=>:permalink, User=>:login) do
resources :users do
resources :articles
end
end
Generating
resource(@user, @article)
# => /users/bryan/articles/hello-world

23. Redirecting legacy URLs
Legacy URL
/articles/123-hello-world
New URL
/articles/hello-world

24. In the Controller?
match(quot;/articles/:idquot;).
to(:controller => quot;articlesquot;, :action => quot;showquot;)

25. Use regex to match?
match(quot;/articles/:idquot;, :id => /^d+-/).
to(:controller => quot;articlesquot;, :action => quot;legacyquot;)
match(quot;/articles/:urlquot;).
to(:controller => quot;articlesquot;, :action => quot;showquot;)

26. Or, add your own logic!
match(quot;/articles/:urlquot;).defer_to do |request, params|
if article = Article.first(:url => params[:url])
params.merge(:article => article)
elsif article = Article.first(:id => params[:url])
redirect url(:article, article.url)
else
false
end
end

27. Checking authentication
match(quot;/secretquot;).defer_to do |request, params|
if request.session.authenticated?
params
end
end

28. Thanks!

29. Thanks!