Add support for calling nested direct routes (#28462)

Not all requirements can be expressed in terms of polymorphic url
options so add a `route_for` method that allows calling another
direct route (or regular named route) which a set of arguments, e.g:

    resources :buckets

    direct :recordable do |recording|
      route_for(:bucket, recording.bucket)
    end

    direct :threadable do |threadable|
      route_for(:recordable, threadable.parent)
    end

This maintains the context of the original caller, e.g.

    threadable_path(threadable) # => /buckets/1
    threadable_url(threadable)  # => http://example.com/buckets/1

4 files changed, 48 insertions, 32 deletions

diff --git a/actionpack/lib/action_dispatch/routing/polymorphic_routes.rb b/actionpack/lib/action_dispatch/routing/polymorphic_routes.rb
index 984ded1ff5..e89ea8b21d 100644
--- a/actionpack/lib/action_dispatch/routing/polymorphic_routes.rb
+++ b/actionpack/lib/action_dispatch/routing/polymorphic_routes.rb
@@ -40,7 +40,7 @@ module ActionDispatch
     #
     # Example usage:
     #
-    #   edit_polymorphic_path(@post)              # => "/posts/1/edit"
+    #   edit_polymorphic_path(@post)           # => "/posts/1/edit"
     #   polymorphic_path(@post, format: :pdf)  # => "/posts/1.pdf"
     #
     # == Usage with mounted engines
@@ -104,7 +104,7 @@ module ActionDispatch
         end
 
         if mapping = polymorphic_mapping(record_or_hash_or_array)
-          return mapping.call(self, [record_or_hash_or_array, options])
+          return mapping.call(self, [record_or_hash_or_array, options], false)
         end
 
         opts   = options.dup
@@ -128,7 +128,7 @@ module ActionDispatch
         end
 
         if mapping = polymorphic_mapping(record_or_hash_or_array)
-          return mapping.call(self, [record_or_hash_or_array, options], only_path: true)
+          return mapping.call(self, [record_or_hash_or_array, options], true)
         end
 
         opts   = options.dup
@@ -273,7 +273,7 @@ module ActionDispatch
 
           def handle_model_call(target, record)
             if mapping = polymorphic_mapping(target, record)
-              mapping.call(target, [record], only_path: suffix == "path")
+              mapping.call(target, [record], suffix == "path")
             else
               method, args = handle_model(record)
               target.send(method, *args)
diff --git a/actionpack/lib/action_dispatch/routing/route_set.rb b/actionpack/lib/action_dispatch/routing/route_set.rb
index 118dec2ad4..8a9a48938b 100644
--- a/actionpack/lib/action_dispatch/routing/route_set.rb
+++ b/actionpack/lib/action_dispatch/routing/route_set.rb
@@ -164,13 +164,13 @@ module ActionDispatch
 
           @path_helpers_module.module_eval do
             define_method(:"#{name}_path") do |*args|
-              helper.call(self, args, only_path: true)
+              helper.call(self, args, true)
             end
           end
 
           @url_helpers_module.module_eval do
             define_method(:"#{name}_url") do |*args|
-              helper.call(self, args)
+              helper.call(self, args, false)
             end
           end
         end
@@ -509,6 +509,10 @@ module ActionDispatch
               @_proxy.url_for(options)
             end
 
+            def route_for(name, *args)
+              @_proxy.route_for(name, *args)
+            end
+
             def optimize_routes_generation?
               @_proxy.optimize_routes_generation?
             end
@@ -613,26 +617,14 @@ module ActionDispatch
           @block = block
         end
 
-        def call(t, args, outer_options = {})
+        def call(t, args, only_path = false)
           options = args.extract_options!
-          url_options = eval_block(t, args, options)
-
-          case url_options
-          when String
-            t.url_for(url_options)
-          when Hash
-            t.url_for(url_options.merge(outer_options))
-          when ActionController::Parameters
-            if url_options.permitted?
-              t.url_for(url_options.to_h.merge(outer_options))
-            else
-              raise ArgumentError, "Generating a URL from non sanitized request parameters is insecure!"
-            end
-          when Array
-            opts = url_options.extract_options!
-            t.url_for(url_options.push(opts.merge(outer_options)))
+          url = t.url_for(eval_block(t, args, options))
+
+          if only_path
+            "/" + url.partition(%r{(?<!/)/(?!/)}).last
           else
-            t.url_for([url_options, outer_options])
+            url
           end
         end
 
diff --git a/actionpack/lib/action_dispatch/routing/url_for.rb b/actionpack/lib/action_dispatch/routing/url_for.rb
index 3e564f13d8..d199bece96 100644
--- a/actionpack/lib/action_dispatch/routing/url_for.rb
+++ b/actionpack/lib/action_dispatch/routing/url_for.rb
@@ -192,6 +192,10 @@ module ActionDispatch
         end
       end
 
+      def route_for(name, *args) # :nodoc:
+        public_send(:"#{name}_url", *args)
+      end
+
       protected
 
         def optimize_routes_generation?
diff --git a/actionpack/test/dispatch/routing/custom_url_helpers_test.rb b/actionpack/test/dispatch/routing/custom_url_helpers_test.rb
index f85b989892..cb5ca5888b 100644
--- a/actionpack/test/dispatch/routing/custom_url_helpers_test.rb
+++ b/actionpack/test/dispatch/routing/custom_url_helpers_test.rb
@@ -4,18 +4,23 @@ class TestCustomUrlHelpers < ActionDispatch::IntegrationTest
   class Linkable
     attr_reader :id
 
+    def self.name
+      super.demodulize
+    end
+
     def initialize(id)
       @id = id
     end
 
     def linkable_type
-      self.class.name.demodulize.underscore
+      self.class.name.underscore
     end
   end
 
   class Category < Linkable; end
   class Collection < Linkable; end
   class Product < Linkable; end
+  class Manufacturer < Linkable; end
 
   class Model
     extend ActiveModel::Naming
@@ -79,7 +84,7 @@ class TestCustomUrlHelpers < ActionDispatch::IntegrationTest
     get "/media/:id", to: "media#show", as: :media
     get "/pages/:id", to: "pages#show", as: :page
 
-    resources :categories, :collections, :products
+    resources :categories, :collections, :products, :manufacturers
 
     namespace :admin do
       get "/dashboard", to: "dashboard#index"
@@ -89,6 +94,7 @@ class TestCustomUrlHelpers < ActionDispatch::IntegrationTest
     direct("string")  { "http://www.rubyonrails.org" }
     direct(:helper)   { basket_url }
     direct(:linkable) { |linkable| [:"#{linkable.linkable_type}", { id: linkable.id }] }
+    direct(:nested)   { |linkable| route_for(:linkable, linkable) }
     direct(:params)   { |params| params }
     direct(:symbol)   { :basket }
     direct(:hash)     { { controller: "basket", action: "show" } }
@@ -102,6 +108,7 @@ class TestCustomUrlHelpers < ActionDispatch::IntegrationTest
 
     resolve("Article") { |article| [:post, { id: article.id }] }
     resolve("Basket") { |basket| [:basket] }
+    resolve("Manufacturer") { |manufacturer| route_for(:linkable, manufacturer) }
     resolve("User", anchor: "details") { |user, options| [:profile, options] }
     resolve("Video") { |video| [:media, { id: video.id }] }
     resolve(%w[Page CategoryPage ProductPage]) { |page| [:page, { id: page.id }] }
@@ -119,6 +126,7 @@ class TestCustomUrlHelpers < ActionDispatch::IntegrationTest
     @category = Category.new("1")
     @collection = Collection.new("2")
     @product = Product.new("3")
+    @manufacturer = Manufacturer.new("apple")
     @basket = Basket.new
     @user = User.new
     @video = Video.new("4")
@@ -136,14 +144,14 @@ class TestCustomUrlHelpers < ActionDispatch::IntegrationTest
   end
 
   def test_direct_paths
-    assert_equal "http://www.rubyonrails.org", website_path
-    assert_equal "http://www.rubyonrails.org", Routes.url_helpers.website_path
+    assert_equal "/", website_path
+    assert_equal "/", Routes.url_helpers.website_path
 
-    assert_equal "http://www.rubyonrails.org", string_path
-    assert_equal "http://www.rubyonrails.org", Routes.url_helpers.string_path
+    assert_equal "/", string_path
+    assert_equal "/", Routes.url_helpers.string_path
 
-    assert_equal "http://www.example.com/basket", helper_url
-    assert_equal "http://www.example.com/basket", Routes.url_helpers.helper_url
+    assert_equal "/basket", helper_path
+    assert_equal "/basket", Routes.url_helpers.helper_path
 
     assert_equal "/categories/1", linkable_path(@category)
     assert_equal "/categories/1", Routes.url_helpers.linkable_path(@category)
@@ -152,6 +160,9 @@ class TestCustomUrlHelpers < ActionDispatch::IntegrationTest
     assert_equal "/products/3", linkable_path(@product)
     assert_equal "/products/3", Routes.url_helpers.linkable_path(@product)
 
+    assert_equal "/categories/1", nested_path(@category)
+    assert_equal "/categories/1", Routes.url_helpers.nested_path(@category)
+
     assert_equal "/", params_path(@safe_params)
     assert_equal "/", Routes.url_helpers.params_path(@safe_params)
     assert_raises(ArgumentError) { params_path(@unsafe_params) }
@@ -192,6 +203,9 @@ class TestCustomUrlHelpers < ActionDispatch::IntegrationTest
     assert_equal "http://www.example.com/products/3", linkable_url(@product)
     assert_equal "http://www.example.com/products/3", Routes.url_helpers.linkable_url(@product)
 
+    assert_equal "http://www.example.com/categories/1", nested_url(@category)
+    assert_equal "http://www.example.com/categories/1", Routes.url_helpers.nested_url(@category)
+
     assert_equal "http://www.example.com/", params_url(@safe_params)
     assert_equal "http://www.example.com/", Routes.url_helpers.params_url(@safe_params)
     assert_raises(ArgumentError) { params_url(@unsafe_params) }
@@ -244,6 +258,9 @@ class TestCustomUrlHelpers < ActionDispatch::IntegrationTest
     assert_equal "/pages/8", polymorphic_path(@product_page)
     assert_equal "/pages/8", Routes.url_helpers.polymorphic_path(@product_page)
     assert_equal "/pages/8", ActionDispatch::Routing::PolymorphicRoutes::HelperMethodBuilder.path.handle_model_call(self, @product_page)
+
+    assert_equal "/manufacturers/apple", polymorphic_path(@manufacturer)
+    assert_equal "/manufacturers/apple", Routes.url_helpers.polymorphic_path(@manufacturer)
   end
 
   def test_resolve_urls
@@ -277,6 +294,9 @@ class TestCustomUrlHelpers < ActionDispatch::IntegrationTest
     assert_equal "http://www.example.com/pages/8", polymorphic_url(@product_page)
     assert_equal "http://www.example.com/pages/8", Routes.url_helpers.polymorphic_url(@product_page)
     assert_equal "http://www.example.com/pages/8", ActionDispatch::Routing::PolymorphicRoutes::HelperMethodBuilder.url.handle_model_call(self, @product_page)
+
+    assert_equal "http://www.example.com/manufacturers/apple", polymorphic_url(@manufacturer)
+    assert_equal "http://www.example.com/manufacturers/apple", Routes.url_helpers.polymorphic_url(@manufacturer)
   end
 
   def test_defining_direct_inside_a_scope_raises_runtime_error