Fixed polymorphic_url to be able to handle singleton resources.

Example usage:
polymorphic_url([:admin, @user, :blog, @post]) # => admin_user_blog_post_url(@user, @post)

[#461 state:resolved]

actionpack/CHANGELOG

 *Edge*
 
+* Fix polymorphic_url with singleton resources.  #461 [Tammer Saleh]
+
 * Replaced TemplateFinder abstraction with ViewLoadPaths [Josh Peek]
 
 * Added block-call style to link_to [Sam Stephenson/DHH]. Example:

actionpack/lib/action_controller/polymorphic_routes.rb

@@ -48,6 +48,9 @@ module PolymorphicRoutes
     #
     #   # calls post_url(post)
     #   polymorphic_url(post) # => "http://example.com/posts/1"
+    #   polymorphic_url([blog, post]) # => "http://example.com/blogs/1/posts/1"
+    #   polymorphic_url([:admin, blog, post]) # => "http://example.com/admin/blogs/1/posts/1"
+    #   polymorphic_url([user, :blog, post]) # => "http://example.com/users/1/blog/posts/1"
     #
     # ==== Options
     #
@@ -83,8 +86,6 @@ def polymorphic_url(record_or_hash_or_array, options = {})
         else        [ record_or_hash_or_array ]
       end
 
-      args << format if format
-
       inflection =
         case
         when options[:action].to_s == "new"
@@ -96,6 +97,9 @@ def polymorphic_url(record_or_hash_or_array, options = {})
         else
           :singular
         end
+
+      args.delete_if {|arg| arg.is_a?(Symbol) || arg.is_a?(String)}
+      args << format if format
       
       named_route = build_named_route_call(record_or_hash_or_array, namespace, inflection, options)
       send!(named_route, *args)
@@ -136,11 +140,19 @@ def build_named_route_call(records, namespace, inflection, options = {})
         else
           record = records.pop
           route = records.inject("") do |string, parent|
-            string << "#{RecordIdentifier.send!("singular_class_name", parent)}_"
+            if parent.is_a?(Symbol) || parent.is_a?(String)
+              string << "#{parent}_"
+            else
+              string << "#{RecordIdentifier.send!("singular_class_name", parent)}_"
+            end
           end
         end
 
-        route << "#{RecordIdentifier.send!("#{inflection}_class_name", record)}_"
+        if record.is_a?(Symbol) || record.is_a?(String)
+          route << "#{record}_"
+        else
+          route << "#{RecordIdentifier.send!("#{inflection}_class_name", record)}_"
+        end
 
         action_prefix(options) + namespace + route + routing_type(options).to_s
       end
@@ -163,16 +175,17 @@ def extract_format(record_or_hash_or_array, options)
         end
       end
       
+      # Remove the first symbols from the array and return the url prefix
+      # implied by those symbols.
       def extract_namespace(record_or_hash_or_array)
-        returning "" do |namespace|
-          if record_or_hash_or_array.is_a?(Array)
-            record_or_hash_or_array.delete_if do |record_or_namespace|
-              if record_or_namespace.is_a?(String) || record_or_namespace.is_a?(Symbol)
-                namespace << "#{record_or_namespace}_"
-              end
-            end
-          end  
+        return "" unless record_or_hash_or_array.is_a?(Array)
+
+        namespace_keys = []
+        while (key = record_or_hash_or_array.first) && key.is_a?(String) || key.is_a?(Symbol)
+          namespace_keys << record_or_hash_or_array.shift
         end
+
+        namespace_keys.map {|k| "#{k}_"}.join
       end
   end
 end

actionpack/test/controller/polymorphic_routes_test.rb

@@ -118,6 +118,39 @@ def test_nested_with_array_and_namespace
       polymorphic_url([:site, :admin, @article, @response, @tag])
     end
 
+    def test_nesting_with_array_ending_in_singleton_resource
+      expects(:article_response_url).with(@article)
+      polymorphic_url([@article, :response])
+    end
+
+    def test_nesting_with_array_containing_singleton_resource
+      @tag = Tag.new
+      @tag.save
+      expects(:article_response_tag_url).with(@article, @tag)
+      polymorphic_url([@article, :response, @tag])
+    end
+
+    def test_nesting_with_array_containing_namespace_and_singleton_resource
+      @tag = Tag.new
+      @tag.save
+      expects(:admin_article_response_tag_url).with(@article, @tag)
+      polymorphic_url([:admin, @article, :response, @tag])
+    end
+
+    def test_nesting_with_array_containing_singleton_resource_and_format
+      @tag = Tag.new
+      @tag.save
+      expects(:formatted_article_response_tag_url).with(@article, @tag, :pdf)
+      formatted_polymorphic_url([@article, :response, @tag, :pdf])
+    end
+
+    def test_nesting_with_array_containing_singleton_resource_and_format_option
+      @tag = Tag.new
+      @tag.save
+      expects(:article_response_tag_url).with(@article, @tag, :pdf)
+      polymorphic_url([@article, :response, @tag], :format => :pdf)
+    end
+
     # TODO: Needs to be updated to correctly know about whether the object is in a hash or not
     def xtest_with_hash
       expects(:article_url).with(@article)