class 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

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

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 ::prepare block will defined in context of this behavior.

Examples

::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

routes[RW]

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

:api: private

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<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
def extensions(&block)
  Router::Behavior.class_eval(&block)
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<Array>

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

last<Array>

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
def prepare(first = [], last = [], &block)
  @routes = []
  root_behavior._with_proxy(&block)
  @routes = first + @routes + last
  compile
  self
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
def reset!
  class << self
    alias_method :match, :match_before_compilation
  end
  self.routes, self.named_routes, self.resource_routes = [], {}, {}
end
resource(*args) click to toggle source

Generates a URL from the resource(s)

Parameters

resources<Symbol,Object>

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<Hash>

Any extra parameters needed to generate the route.

Returns

String

The generated URL

:api: plugin

# File lib/merb-core/dispatch/router.rb, line 255
def resource(*args)
  defaults = args.pop
  options  = extract_options_from_args!(args) || {}
  key      = []
  params   = []
  
  args.each do |arg|
    if arg.is_a?(Symbol) || arg.is_a?(String)
      key << arg.to_s
    else
      key << arg.class.to_s
      params << arg
    end
  end
  
  unless route = Merb::Router.resource_routes[key]
    raise Merb::Router::GenerationError, "Resource route not found: #{args.inspect}"
  end

  params << options
  
  route.generate(params, defaults, true)
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<Merb::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
def route_for(request)
  index, params = if @around_match
    send(@around_match, request) { match(request) }
  else
    match(request)
  end
  route = routes[index] if index
  if !route
    raise ControllerExceptions::NotFound, 
      "No routes match the request: #{request.uri}"
  end
  [route, params]
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<Symbol>

The name of the route.

args<Hash>

Parameters for the route generation.

Parameters(Default Route)

args<Hash>

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

Parameters(Anonymous Parameters)

name<Symbol>

The name of the route.

args<Array>

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

::prepare do

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

end

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

Default Route

::prepare do

default_routes

end

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

Anonymous Paramters

::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
def url(name, *args)
  if name.is_a?(Route)
    route = name
  else
    unless name.is_a?(Symbol)
      args.unshift(name)
      name = :default
    end

    unless route = Merb::Router.named_routes[name]
      raise Merb::Router::GenerationError, "Named route not found: #{name}"
    end
  end
  
  defaults = args.pop
  
  route.generate(args, defaults)
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
def compile
  if routes.any?
    begin
      eval(compiled_statement, binding, "Generated Code for Router", 1)
    rescue SyntaxError => e
      puts "\nGenerated code failed:\n #{compiled_statement}"
      raise e
    end
  else
    reset!
  end
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
def compiled_statement
  @compiler_mutex.synchronize do
    condition_keys, if_statements = Set.new, ""
    
    routes.each_with_index do |route, i|
      route.freeze
      route.conditions.keys.each { |key| condition_keys << key }
      if_statements << route.compiled_statement(i == 0)
    end
    
    statement =  "public\ndef match(request)\n"
    statement << condition_keys.inject("") do |cached, key|
      cached << "  cached_#{key} = request.#{key}.to_s\n"
    end
    statement <<    if_statements
    statement << "  else\n"
    statement << "    [nil, {}]\n"
    statement << "  end\n"
    statement << "end"
  end
end