This fix allows the polymorphic_method in the HelperMethodBuilder cla…

…ss in polymorphic_routes.rb discern whether or not a singular resource is being passed into it. If it finds a singular resource it will pass in format: nil to the options so that we can have an edited object using the patch method get sent to the proper URL instead of appending a period and number to the end.

actionpack/lib/action_dispatch/routing/polymorphic_routes.rb

@@ -206,7 +206,6 @@ def self.plural(prefix, suffix)
 
           def self.polymorphic_method(recipient, record_or_hash_or_array, action, type, options)
             builder = get action, type
-
             case record_or_hash_or_array
             when Array
               record_or_hash_or_array = record_or_hash_or_array.compact
@@ -228,10 +227,12 @@ def self.polymorphic_method(recipient, record_or_hash_or_array, action, type, op
             else
               method, args = builder.handle_model record_or_hash_or_array
             end
+            method_type = method.delete_suffix "_path"
 
-            if options.empty?
+            if options.empty? && method_type != method_type.singularize
               recipient.public_send(method, *args)
             else
+              options[:format] ||= nil
               recipient.public_send(method, *args, options)
             end
           end

actionpack/test/dispatch/prefix_generation_test.rb

@@ -22,6 +22,23 @@ def klass.name; self end
     def to_model; self; end
     def persisted?; true; end
   end
+  class Author
+    extend ActiveModel::Naming
+
+    def to_param
+      "1"
+    end
+
+    def self.model_name
+      klass = +"Author"
+      def klass.name; self end
+
+      ActiveModel::Name.new(klass)
+    end
+
+    def to_model; self; end
+    def persisted?; true; end
+  end
 
   class WithMountedEngine < ActionDispatch::IntegrationTest
     class BlogEngine < Rails::Engine
@@ -46,6 +63,8 @@ class BlogEngine < Rails::Engine
         get "/absolute_option_redirect", to: redirect(path: "/foo")
         get "/absolute_custom_root",     to: redirect { |params, request| "/" }
         get "/absolute_custom_redirect", to: redirect { |params, request| "/foo" }
+
+        resource :author
       end
     end
 
@@ -327,6 +346,14 @@ def setup
       assert_equal "http://www.example.com/awesome/blog/posts/1", path
     end
 
+    test "[OBJECT] generating engine's route with polymorphic_url from singular resource" do
+      path = engine_object.polymorphic_path(Author.new)
+      assert_equal "/awesome/blog/author", path
+
+      path = engine_object.polymorphic_url(Author.new, host: "www.example.com")
+      assert_equal "http://www.example.com/awesome/blog/author", path
+    end
+
     private
       def verify_redirect(url, status = 301)
         assert_equal status, response.status