Merge pull request #29662 from deivid-rodriguez/engine_multiple_mount_points

Allow mounting same engine under several locations

actionpack/lib/action_dispatch/routing/mapper.rb

@@ -652,19 +652,26 @@ module ActionDispatch
           def define_generate_prefix(app, name)
             _route = @set.named_routes.get name
             _routes = @set
-            app.routes.define_mounted_helper(name)
+
-            app.routes.extend Module.new {
+            script_namer = ->(options) do
-              def optimize_routes_generation?; false; end
-              define_method :find_script_name do |options|
-                if options.key? :script_name
-                  super(options)
-                else
               prefix_options = options.slice(*_route.segment_keys)
               prefix_options[:relative_url_root] = "".freeze
               # We must actually delete prefix segment keys to avoid passing them to next url_for.
               _route.segment_keys.each { |k| options.delete(k) }
               _routes.url_helpers.send("#{name}_path", prefix_options)
             end
+
+            app.routes.define_mounted_helper(name, script_namer)
+
+            app.routes.extend Module.new {
+              def optimize_routes_generation?; false; end
+
+              define_method :find_script_name do |options|
+                if options.key? :script_name
+                  super(options)
+                else
+                  script_namer.call(options)
+                end
               end
             }
           end

actionpack/lib/action_dispatch/routing/route_set.rb

@@ -449,7 +449,7 @@ module ActionDispatch
         MountedHelpers
       end
 
-      def define_mounted_helper(name)
+      def define_mounted_helper(name, script_namer = nil)
         return if MountedHelpers.method_defined?(name)
 
         routes = self
@@ -457,7 +457,7 @@ module ActionDispatch
 
         MountedHelpers.class_eval do
           define_method "_#{name}" do
-            RoutesProxy.new(routes, _routes_context, helpers)
+            RoutesProxy.new(routes, _routes_context, helpers, script_namer)
           end
         end
 

actionpack/lib/action_dispatch/routing/routes_proxy.rb

@@ -8,9 +8,10 @@ module ActionDispatch
       attr_accessor :scope, :routes
       alias :_routes :routes
 
-      def initialize(routes, scope, helpers)
+      def initialize(routes, scope, helpers, script_namer = nil)
         @routes, @scope = routes, scope
         @helpers = helpers
+        @script_namer = script_namer
       end
 
       def url_options
@@ -29,7 +30,9 @@ module ActionDispatch
           self.class.class_eval <<-RUBY, __FILE__, __LINE__ + 1
             def #{method}(*args)
               options = args.extract_options!
-              args << url_options.merge((options || {}).symbolize_keys)
+              options = url_options.merge((options || {}).symbolize_keys)
+              options.reverse_merge!(script_name: @script_namer.call(options)) if @script_namer
+              args << options
               @helpers.#{method}(*args)
             end
           RUBY

railties/CHANGELOG.md

@@ -1,3 +1,9 @@
+*   Allow mounting the same engine several times in different locations.
+
+    Fixes #20204.
+
+    *David Rodríguez*
+
 *   Clear screenshot files in `tmp:clear` task.
 
     *Yuji Yaginuma*

railties/test/railties/engine_test.rb

@@ -1341,6 +1341,92 @@ YAML
       assert_equal "/foo/bukkits/bukkit", last_response.body
     end
 
+    test "isolated engine can be mounted under multiple static locations" do
+      app_file "app/controllers/foos_controller.rb", <<-RUBY
+        class FoosController < ApplicationController
+          def through_fruits
+            render plain: fruit_bukkits.posts_path
+          end
+
+          def through_vegetables
+            render plain: vegetable_bukkits.posts_path
+          end
+        end
+      RUBY
+
+      app_file "config/routes.rb", <<-RUBY
+        Rails.application.routes.draw do
+          scope "/fruits" do
+            mount Bukkits::Engine => "/bukkits", as: :fruit_bukkits
+          end
+
+          scope "/vegetables" do
+            mount Bukkits::Engine => "/bukkits", as: :vegetable_bukkits
+          end
+
+          get "/through_fruits" => "foos#through_fruits"
+          get "/through_vegetables" => "foos#through_vegetables"
+        end
+      RUBY
+
+      @plugin.write "config/routes.rb", <<-RUBY
+        Bukkits::Engine.routes.draw do
+          resources :posts, only: :index
+        end
+      RUBY
+
+      boot_rails
+
+      get("/through_fruits")
+      assert_equal "/fruits/bukkits/posts", last_response.body
+
+      get("/through_vegetables")
+      assert_equal "/vegetables/bukkits/posts", last_response.body
+    end
+
+    test "isolated engine can be mounted under multiple dynamic locations" do
+      app_file "app/controllers/foos_controller.rb", <<-RUBY
+        class FoosController < ApplicationController
+          def through_fruits
+            render plain: fruit_bukkits.posts_path(fruit_id: 1)
+          end
+
+          def through_vegetables
+            render plain: vegetable_bukkits.posts_path(vegetable_id: 1)
+          end
+        end
+      RUBY
+
+      app_file "config/routes.rb", <<-RUBY
+        Rails.application.routes.draw do
+          resources :fruits do
+            mount Bukkits::Engine => "/bukkits"
+          end
+
+          resources :vegetables do
+            mount Bukkits::Engine => "/bukkits"
+          end
+
+          get "/through_fruits" => "foos#through_fruits"
+          get "/through_vegetables" => "foos#through_vegetables"
+        end
+      RUBY
+
+      @plugin.write "config/routes.rb", <<-RUBY
+        Bukkits::Engine.routes.draw do
+          resources :posts, only: :index
+        end
+      RUBY
+
+      boot_rails
+
+      get("/through_fruits")
+      assert_equal "/fruits/1/bukkits/posts", last_response.body
+
+      get("/through_vegetables")
+      assert_equal "/vegetables/1/bukkits/posts", last_response.body
+    end
+
   private
     def app
       Rails.application