1 files changed, 51 insertions, 31 deletions

diff --git a/actionview/lib/action_view/rendering.rb b/actionview/lib/action_view/rendering.rb
index 4e5fdfbb2d..5a06bd9da6 100644
--- a/actionview/lib/action_view/rendering.rb
+++ b/actionview/lib/action_view/rendering.rb
@@ -26,6 +26,13 @@ module ActionView
     extend ActiveSupport::Concern
     include ActionView::ViewPaths
 
+    attr_reader :rendered_format
+
+    def initialize
+      @rendered_format = nil
+      super
+    end
+
     # Overwrite process to setup I18n proxy.
     def process(*) #:nodoc:
       old_config, I18n.config = I18n.config, I18nProxy.new(I18n.config, lookup_context)
@@ -35,47 +42,59 @@ module ActionView
     end
 
     module ClassMethods
-      def view_context_class
-        @view_context_class ||= begin
-          supports_path = supports_path?
-          routes  = respond_to?(:_routes)  && _routes
-          helpers = respond_to?(:_helpers) && _helpers
-
-          Class.new(ActionView::Base) do
-            if routes
-              include routes.url_helpers(supports_path)
-              include routes.mounted_helpers
-            end
-
-            if helpers
-              include helpers
-            end
+      def _routes
+      end
+
+      def _helpers
+      end
+
+      def build_view_context_class(klass, supports_path, routes, helpers)
+        Class.new(klass) do
+          if routes
+            include routes.url_helpers(supports_path)
+            include routes.mounted_helpers
+          end
+
+          if helpers
+            include helpers
           end
         end
       end
-    end
 
-    attr_internal_writer :view_context_class
+      def view_context_class
+        klass = ActionView::LookupContext::DetailsKey.view_context_class(ActionView::Base)
+
+        @view_context_class ||= build_view_context_class(klass, supports_path?, _routes, _helpers)
+
+        if klass.changed?(@view_context_class)
+          @view_context_class = build_view_context_class(klass, supports_path?, _routes, _helpers)
+        end
+
+        @view_context_class
+      end
+    end
 
     def view_context_class
-      @_view_context_class ||= self.class.view_context_class
+      self.class.view_context_class
     end
 
     # An instance of a view class. The default view class is ActionView::Base.
     #
     # The view class must have the following methods:
-    # View.new[lookup_context, assigns, controller]
-    #   Create a new ActionView instance for a controller and we can also pass the arguments.
-    # View#render(option)
-    #   Returns String with the rendered template
+    #
+    # * <tt>View.new(lookup_context, assigns, controller)</tt> — Create a new
+    #   ActionView instance for a controller and we can also pass the arguments.
+    #
+    # * <tt>View#render(option)</tt> — Returns String with the rendered template.
     #
     # Override this method in a module to change the default behavior.
     def view_context
-      view_context_class.new(view_renderer, view_assigns, self)
+      view_context_class.new(lookup_context, view_assigns, self)
     end
 
     # Returns an object that is able to render templates.
     def view_renderer # :nodoc:
+      # Lifespan: Per controller
       @_view_renderer ||= ActionView::Renderer.new(lookup_context)
     end
 
@@ -84,10 +103,6 @@ module ActionView
       _render_template(options)
     end
 
-    def rendered_format
-      Template::Types[lookup_context.rendered_format]
-    end
-
     private
 
       # Find and render a template based on the options given.
@@ -97,17 +112,22 @@ module ActionView
         context = view_context
 
         context.assign assigns if assigns
-        lookup_context.rendered_format = nil if options[:formats]
         lookup_context.variants = variant if variant
 
-        view_renderer.render(context, options)
+        rendered_template = context.in_rendering_context(options) do |renderer|
+          renderer.render_to_object(context, options)
+        end
+
+        rendered_format = rendered_template.format || lookup_context.formats.first
+        @rendered_format = Template::Types[rendered_format]
+
+        rendered_template.body
       end
 
       # Assign the rendered format to look up context.
       def _process_format(format)
         super
-        lookup_context.formats = [format.to_sym]
-        lookup_context.rendered_format = lookup_context.formats.first
+        lookup_context.formats = [format.to_sym] if format.to_sym
       end
 
       # Normalize args by converting render "foo" to render :action => "foo" and