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Merb::Router

Router stores route definitions and finds the first route that matches the incoming request URL.

Then information from route is used by dispatcher to call action on the controller.

Routes compilation.

The most interesting method of Router (and heart of route matching machinery) is match method generated on the fly from routes definitions. It is called routes compilation. Generated match method body contains one if/elsif statement that picks the first matching route definition and sets values to named parameters of the route.

Compilation is synchronized by mutex.

Attributes

routes[RW]

An array containing all the application routes in order of priority.

:api: private

named_routes[RW]

A hash containing all the named application routes. The names are absolute (as in, all routes named in a namespace will contain the name of the namespace).

:api: private

resource_routes[RW]

A hash of all the application resource routes. The key of the hash is an array with each element containing the “path” for the resource for example, given the following resource routes:

resources :users do

  resources :comments

end

The show comment route will have a key of [“User”, “Comment”]

:api: private

root_behavior[RW]

The starting point for route definition. Any route defined in a Merb::Router.prepare block will defined in context of this behavior.

Examples

Merb::Router.root_behavior = Merb::Router.root_bavior.match(“/hello”)

In the previous example, all routes will have the path prefix /hello. It is important to note that this attribute must be set before any routes are defined in order for the behavior to be applied to the routes.

:api: plugin

around_match[RW]

A block that will be run around route matching. This block must yield in order for the actual matching to happen.

:api: plugin

Public Class Methods

extensions(&block) click to toggle source

Add functionality to the router. This can be in the form of including a new module or directly defining new methods.

Parameters

&block

A block of code used to extend the route builder with. This can be including a module or directly defining some new methods that should be available to building routes.

Returns

nil

Example

  Merb::Router.extensions do
    def domain(name, domain, options={}, &block)
      match(:domain => domain).namespace(name, :path => nil, &block)
    end
  end

In this case, a method ‘domain’ will be available to the route builder which will create namespaces around domains instead of path prefixes.

This can then be used as follows.

  Merb::Router.prepare do
    domain(:admin, "my-admin.com") do
      # ... routes come here ...
    end
  end

:api: public

     # File lib/merb-core/dispatch/router.rb, line 310
310:       def extensions(&block)
311:         Router::Behavior.class_eval(&block)
312:       end
prepare(first = [], last = [], &block) click to toggle source

Creates a route building context and evaluates the block in it. A copy of root_behavior (and instance of Behavior) is copied as the context.

Parameters

first

An array containing routes that should be prepended to the routes defined in the block.

last

An array containing routes that should be appended to the routes defined in the block.

Returns

Merb::Router

Returns self to allow chaining of methods.

:api: public

     # File lib/merb-core/dispatch/router.rb, line 103
103:       def prepare(first = [], last = [], &block)
104:         @routes = []
105:         root_behavior._with_proxy(&block)
106:         @routes = first + @routes + last
107:         compile
108:         self
109:       end
reset!() click to toggle source

Clears the routing table. Route generation and request matching won’t work anymore until a new routing table is built.

:api: private

     # File lib/merb-core/dispatch/router.rb, line 115
115:       def reset!
116:         class << self
117:           alias_method :match, :match_before_compilation
118:         end
119:         self.routes, self.named_routes, self.resource_routes = [], {}, {}
120:       end
resource(*args) click to toggle source

Generates a URL from the resource(s)

Parameters

resources

The identifiers for the resource route to generate. These can either be symbols or objects. Symbols denote resource collection routes and objects denote the members.

params

Any extra parameters needed to generate the route.

Returns

String

The generated URL

:api: plugin

     # File lib/merb-core/dispatch/router.rb, line 255
255:       def resource(*args)
256:         defaults = args.pop
257:         options  = extract_options_from_args!(args) || {}
258:         key      = []
259:         params   = []
260:         
261:         args.each do |arg|
262:           if arg.is_a?(Symbol) || arg.is_a?(String)
263:             key << arg.to_s
264:           else
265:             key << arg.class.to_s
266:             params << arg
267:           end
268:         end
269:         
270:         unless route = Merb::Router.resource_routes[key]
271:           raise Merb::Router::GenerationError, "Resource route not found: #{args.inspect}"
272:         end
273: 
274:         params << options
275:         
276:         route.generate(params, defaults, true)
277:       end
route_for(request) click to toggle source

Finds route matching URI of the request and returns a tuple of [route index, route params]. This method is called by the dispatcher and isn’t as useful in applications.

Parameters

request

request to match.

Returns

Array[Integer, Hash]

Two-tuple: route index and route parameters. Route parameters are :controller, :action and all the named segments of the route.

:api: private

     # File lib/merb-core/dispatch/router.rb, line 135
135:       def route_for(request)
136:         index, params = if @around_match
137:           send(@around_match, request) { match(request) }
138:         else
139:           match(request)
140:         end
141:         route = routes[index] if index
142:         if !route
143:           raise ControllerExceptions::NotFound, 
144:             "No routes match the request: #{request.uri}"
145:         end
146:         [route, params]
147:       end
url(name, *args) click to toggle source

There are three possible ways to use this method. First, if you have a named route, you can specify the route as the first parameter as a symbol and any paramters in a hash. Second, you can generate the default route by just passing the params hash, just passing the params hash. Finally, you can use the anonymous parameters. This allows you to specify the parameters to a named route in the order they appear in the router.

Parameters(Named Route)

name

The name of the route.

args

Parameters for the route generation.

Parameters(Default Route)

args

Parameters for the route generation. This route will use the default route.

Parameters(Anonymous Parameters)

name

The name of the route.

args

An array of anonymous parameters to generate the route with. These parameters are assigned to the route parameters in the order that they are passed.

Returns

String

The generated URL.

Examples

Named Route

Merb::Router.prepare do

  match("/articles/:title").to(:controller => :articles, :action => :show).name("articles")

end

url(:articles, :title => “new_article“)

Default Route

Merb::Router.prepare do

  default_routes

end

url(:controller => “articles”, :action => “new”)

Anonymous Paramters

Merb::Router.prepare do

  match("/articles/:year/:month/:title").to(:controller => :articles, :action => :show).name("articles")

end

url(:articles, 2008, 10, “test_article“)

:api: plugin

     # File lib/merb-core/dispatch/router.rb, line 221
221:       def url(name, *args)
222:         if name.is_a?(Route)
223:           route = name
224:         else
225:           unless name.is_a?(Symbol)
226:             args.unshift(name)
227:             name = :default
228:           end
229: 
230:           unless route = Merb::Router.named_routes[name]
231:             raise Merb::Router::GenerationError, "Named route not found: #{name}"
232:           end
233:         end
234:         
235:         defaults = args.pop
236:         
237:         route.generate(args, defaults)
238:       end

Private Class Methods

compile() click to toggle source

Compiles the routes and creates the match method.

:api: private

     # File lib/merb-core/dispatch/router.rb, line 319
319:       def compile
320:         if routes.any?
321:           begin
322:             eval(compiled_statement, binding, "Generated Code for Router", 1)
323:           rescue SyntaxError => e
324:             puts "\nGenerated code failed:\n #{compiled_statement}"
325:             raise e
326:           end
327:         else
328:           reset!
329:         end
330:       end
compiled_statement() click to toggle source

Generates the method for evaluation defining a match method to match a request with the defined routes.

:api: private

     # File lib/merb-core/dispatch/router.rb, line 336
336:       def compiled_statement
337:         @compiler_mutex.synchronize do
338:           condition_keys, if_statements = Set.new, ""
339:           
340:           routes.each_with_index do |route, i|
341:             route.freeze
342:             route.conditions.keys.each { |key| condition_keys << key }
343:             if_statements << route.compiled_statement(i == 0)
344:           end
345:           
346:           statement =  "public\ndef match(request)\n"
347:           statement << condition_keys.inject("") do |cached, key|
348:             cached << "  cached_#{key} = request.#{key}.to_s\n"
349:           end
350:           statement <<    if_statements
351:           statement << "  else\n"
352:           statement << "    [nil, {}]\n"
353:           statement << "  end\n"
354:           statement << "end"
355:         end
356:       end

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