Allow loading external route files from the router

This feature enables the ability to load an
external routes file from the router via:
  draw :filename

External routes files go in +config/routes+. This
feature works in both engines and applications.

actionpack/lib/action_dispatch/routing/mapper.rb

@@ -1305,6 +1305,21 @@ def shallow?
           parent_resource.instance_of?(Resource) && @scope[:shallow]
         end
 
+        def draw(name)
+          path = @draw_paths.find do |path|
+            path.join("#{name}.rb").file?
+          end
+
+          unless path
+            msg  = "Your router tried to #draw the external file #{name}.rb,\n" \
+                   "but the file was not found in:\n\n"
+            msg += @draw_paths.map { |path| " * #{path}" }.join("\n")
+            raise msg
+          end
+
+          instance_eval(path.join("#{name}.rb").read)
+        end
+
         # match 'path' => 'controller#action'
         # match 'path', to: 'controller#action'
         # match 'path', 'otherpath', on: :member, via: :get
@@ -1554,6 +1569,7 @@ def name_for_action(as, action) #:nodoc:
 
       def initialize(set) #:nodoc:
         @set = set
+        @draw_paths = set.draw_paths
         @scope = { :path_names => @set.resources_path_names }
       end
 

actionpack/lib/action_dispatch/routing/route_set.rb

@@ -255,6 +255,7 @@ def optimized_helper(route)
       attr_accessor :formatter, :set, :named_routes, :default_scope, :router
       attr_accessor :disable_clear_and_finalize, :resources_path_names
       attr_accessor :default_url_options, :request_class, :valid_conditions
+      attr_accessor :draw_paths
 
       alias :routes :set
 
@@ -266,6 +267,7 @@ def initialize(request_class = ActionDispatch::Request)
         self.named_routes = NamedRouteCollection.new
         self.resources_path_names = self.class.default_resources_path_names.dup
         self.default_url_options = {}
+        self.draw_paths = []
 
         self.request_class = request_class
         @valid_conditions = {}

guides/source/routing.textile

@@ -829,6 +829,24 @@ end
 
 This will create routing helpers such as +magazine_periodical_ads_url+ and +edit_magazine_periodical_ad_path+.
 
+h3. Breaking Up a Large Route File
+
+If you have a large route file that you would like to break up into multiple files, you can use the +#draw+ method in your router:
+
+<ruby>
+draw :admin
+</ruby>
+
+Then, create a file called +config/routes/admin.rb+. Name the file the same as the symbol passed to the +draw+ method). You can then use the normal routing DSL inside that file:
+
+<ruby>
+# in config/routes/admin.rb
+
+namespace :admin do
+  resources :posts
+end
+</ruby>
+
 h3. Inspecting and Testing Routes
 
 Rails offers facilities for inspecting and testing your routes.

railties/lib/rails/engine.rb

@@ -487,6 +487,7 @@ def env_config
 
     def routes
       @routes ||= ActionDispatch::Routing::RouteSet.new
+      @routes.draw_paths.concat paths["config/routes"].paths
       @routes.append(&Proc.new) if block_given?
       @routes
     end
@@ -544,7 +545,7 @@ def load_seed
     end
 
     initializer :add_routing_paths do |app|
-      paths = self.paths["config/routes"].existent
+      paths = self.paths["config/routes.rb"].existent
 
       if routes? || paths.any?
         app.routes_reloader.paths.unshift(*paths)

railties/lib/rails/engine/configuration.rb

@@ -52,7 +52,8 @@ def paths
           paths.add "config/environments", :glob => "#{Rails.env}.rb"
           paths.add "config/initializers", :glob => "**/*.rb"
           paths.add "config/locales",      :glob => "*.{rb,yml}"
-          paths.add "config/routes",       :with => "config/routes.rb"
+          paths.add "config/routes.rb"
+          paths.add "config/routes",       :glob => "**/*.rb"
           paths.add "db"
           paths.add "db/migrate"
           paths.add "db/seeds",            :with => "db/seeds.rb"

railties/lib/rails/paths.rb

@@ -1,3 +1,5 @@
+require "pathname"
+
 module Rails
   module Paths
     # This object is an extended hash that behaves as root of the <tt>Rails::Paths</tt> system.
@@ -114,7 +116,7 @@ def filter_by(constraint)
     class Path
       include Enumerable
 
-      attr_reader :path
+      attr_reader :path, :root
       attr_accessor :glob
 
       def initialize(root, current, paths, options = {})
@@ -180,6 +182,14 @@ def to_ary
         @paths
       end
 
+      def paths
+        raise "You need to set a path root" unless @root.path
+
+        map do |p|
+          Pathname.new(@root.path).join(p)
+        end
+      end
+
       # Expands all paths against the root and return all unique values.
       def expanded
         raise "You need to set a path root" unless @root.path

railties/test/application/paths_test.rb

@@ -50,6 +50,8 @@ def assert_not_in_load_path(*path)
       assert_path @paths["config/locales"],      "config/locales/en.yml"
       assert_path @paths["config/environment"],  "config/environment.rb"
       assert_path @paths["config/environments"], "config/environments/development.rb"
+      assert_path @paths["config/routes.rb"],    "config/routes.rb"
+      assert_path @paths["config/routes"],       "config/routes"
 
       assert_equal root("app", "controllers"), @paths["app/controllers"].expanded.first
     end

railties/test/application/routing_test.rb

@@ -166,6 +166,30 @@ def index
       assert_equal 'WIN', last_response.body
     end
 
+    test "routes drawing from config/routes" do
+      app_file 'config/routes.rb', <<-RUBY
+        AppTemplate::Application.routes.draw do
+          draw :external
+        end
+      RUBY
+
+      app_file 'config/routes/external.rb', <<-RUBY
+        get ':controller/:action'
+      RUBY
+
+      controller :success, <<-RUBY
+        class SuccessController < ActionController::Base
+          def index
+            render :text => "success!"
+          end
+        end
+      RUBY
+
+      app 'development'
+      get '/success/index'
+      assert_equal 'success!', last_response.body
+    end
+
     {"development" => "baz", "production" => "bar"}.each do |mode, expected|
       test "reloads routes when configuration is changed in #{mode}" do
         controller :foo, <<-RUBY

railties/test/paths_test.rb

@@ -29,6 +29,7 @@ def setup
   test "creating a root level path" do
     @root.add "app"
     assert_equal ["/foo/bar/app"], @root["app"].to_a
+    assert_equal [Pathname.new("/foo/bar/app")], @root["app"].paths
   end
 
   test "creating a root level path with options" do
@@ -191,6 +192,7 @@ def setup
     @root["app"] = "/app"
     @root["app"].glob = "*.rb"
     assert_equal "*.rb", @root["app"].glob
+    assert_equal [Pathname.new("/app")], @root["app"].paths
   end
 
   test "it should be possible to override a path's default glob without assignment" do