refactor param parsing middleware to use request objects

this is another place that we should stop directly accessing the env
hash and let the request object take care of that for us

actionpack/lib/action_dispatch/http/request.rb

@@ -339,6 +339,14 @@ module ActionDispatch
       LOCALHOST =~ remote_addr && LOCALHOST =~ remote_ip
     end
 
+    def request_parameters=(params)
+      env["action_dispatch.request.request_parameters".freeze] = params
+    end
+
+    def logger
+      env["action_dispatch.logger".freeze]
+    end
+
     private
       def check_method(name)
         HTTP_METHOD_LOOKUP[name] || raise(ActionController::UnknownHttpMethod, "#{name}, accepted HTTP methods are #{HTTP_METHODS[0...-1].join(', ')}, and #{HTTP_METHODS[-1]}")

actionpack/lib/action_dispatch/middleware/params_parser.rb

@@ -26,30 +26,29 @@ module ActionDispatch
     end
 
     def call(env)
-      default = env["action_dispatch.request.request_parameters"]
-      env["action_dispatch.request.request_parameters"] = parse_formatted_parameters(env, @parsers, default)
+      request = Request.new(env)
+
+      request.request_parameters = parse_formatted_parameters(request, @parsers)
 
       @app.call(env)
     end
 
     private
-      def parse_formatted_parameters(env, parsers, default)
-        request = Request.new(env)
+      def parse_formatted_parameters(request, parsers)
+        return if request.content_length.zero?
 
-        return default if request.content_length.zero?
-
-        strategy = parsers.fetch(request.content_mime_type) { return default }
+        strategy = parsers.fetch(request.content_mime_type) { return nil }
 
         strategy.call(request.raw_post)
 
       rescue => e # JSON or Ruby code block errors
-        logger(env).debug "Error occurred while parsing request parameters.\nContents:\n\n#{request.raw_post}"
+        logger(request).debug "Error occurred while parsing request parameters.\nContents:\n\n#{request.raw_post}"
 
         raise ParseError.new(e.message, e)
       end
 
-      def logger(env)
-        env['action_dispatch.logger'] || ActiveSupport::Logger.new($stderr)
+      def logger(request)
+        request.logger || ActiveSupport::Logger.new($stderr)
       end
   end
 end