provide a request and response to all controllers

Controllers should always have a request and response when responding.
Since we make this The Rule(tm), then controllers don't need to be
somewhere in limbo between "asking a response object for a rack
response" or "I, myself contain a rack response".  This duality leads to
conditionals spread through the codebase that we can delete:

  * https://github.com/rails/rails/blob/85a78d9358aa728298cd020cdc842b55c16f9549/actionpack/lib/action_controller/metal.rb#L221-L223

actionpack/lib/action_controller/metal.rb

@@ -132,6 +132,12 @@ def self.controller_name
       @controller_name ||= name.demodulize.sub(/Controller$/, '').underscore
     end
 
+    def self.make_response!(request)
+      ActionDispatch::Response.new.tap do |res|
+        res.request = request
+      end
+    end
+
     # Delegates to the class' <tt>controller_name</tt>
     def controller_name
       self.class.controller_name
@@ -143,11 +149,10 @@ def controller_name
     # and response object available. You might wish to control the
     # environment and response manually for performance reasons.
 
-    attr_internal :headers, :response, :request
-    delegate :session, :to => "@_request"
+    attr_internal :response, :request
+    delegate :session, :headers, :to => "@_request"
 
     def initialize
-      @_headers = {"Content-Type" => "text/html"}
       @_status = 200
       @_request = nil
       @_response = nil
@@ -168,7 +173,7 @@ def params=(val)
     # in Renderer and Redirector.
 
     def content_type=(type)
-      headers["Content-Type"] = type.to_s
+      response.content_type = type
     end
 
     def content_type
@@ -199,6 +204,7 @@ def status=(status)
 
     def response_body=(body)
       body = [body] unless body.nil? || body.respond_to?(:each)
+      response.body = body
       super
     end
 
@@ -207,12 +213,17 @@ def performed?
       response_body || (response && response.committed?)
     end
 
-    def dispatch(name, request) #:nodoc:
+    def dispatch(name, request, response) #:nodoc:
       set_request!(request)
+      set_response!(response)
       process(name)
       to_a
     end
 
+    def set_response!(response) # :nodoc:
+      @_response = response
+    end
+
     def set_request!(request) #:nodoc:
       @_request = request
       @_request.controller_instance = self
@@ -253,20 +264,26 @@ class << self; deprecate :call; end
     def self.action(name)
       if middleware_stack.any?
         middleware_stack.build(name) do |env|
-          new.dispatch(name, ActionDispatch::Request.new(env))
+          req = ActionDispatch::Request.new(env)
+          res = make_response! req
+          new.dispatch(name, req, res)
         end
       else
-        lambda { |env| new.dispatch(name, ActionDispatch::Request.new(env)) }
+        lambda { |env|
+          req = ActionDispatch::Request.new(env)
+          res = make_response! req
+          new.dispatch(name, req, res)
+        }
       end
     end
 
     # Direct dispatch to the controller.  Instantiates the controller, then
     # executes the action named +name+.
-    def self.dispatch(name, req)
+    def self.dispatch(name, req, res)
       if middleware_stack.any?
-        middleware_stack.build(name) { |env| new.dispatch(name, req) }.call req.env
+        middleware_stack.build(name) { |env| new.dispatch(name, req, res) }.call req.env
       else
-        new.dispatch(name, req)
+        new.dispatch(name, req, res)
       end
     end
   end

actionpack/lib/action_controller/metal/head.rb

@@ -36,6 +36,8 @@ def head(status, options = {})
         headers[key.to_s.dasherize.split('-').each { |v| v[0] = v[0].chr.upcase }.join('-')] = value.to_s
       end
 
+      response.status = Rack::Utils.status_code(status)
+
       self.status = status
       self.location = url_for(location) if location
 
@@ -44,9 +46,6 @@ def head(status, options = {})
       if include_content?(self.response_code)
         self.content_type = content_type || (Mime[formats.first] if formats)
         self.response.charset = false if self.response
-      else
-        headers.delete('Content-Type')
-        headers.delete('Content-Length')
       end
 
       true

actionpack/lib/action_controller/metal/rack_delegation.rb

@@ -12,17 +12,6 @@ module ClassMethods
       def build_with_env(env = {}) #:nodoc:
         new.tap { |c| c.set_request! ActionDispatch::Request.new(env) }
       end
-
-      def make_response!(request)
-        ActionDispatch::Response.new.tap do |res|
-          res.request = request
-        end
-      end
-    end
-
-    def set_request!(request) #:nodoc:
-      super
-      set_response!(request)
     end
 
     def response_body=(body)
@@ -33,11 +22,5 @@ def response_body=(body)
     def reset_session
       @_request.reset_session
     end
-
-    private
-
-    def set_response!(request)
-      @_response = self.class.make_response! request
-    end
   end
 end

actionpack/lib/action_dispatch/http/response.rb

@@ -65,7 +65,7 @@ class Response
     CONTENT_TYPE = "Content-Type".freeze
     SET_COOKIE   = "Set-Cookie".freeze
     LOCATION     = "Location".freeze
-    NO_CONTENT_CODES = [204, 304]
+    NO_CONTENT_CODES = [100, 101, 102, 204, 205, 304]
 
     cattr_accessor(:default_charset) { "utf-8" }
     cattr_accessor(:default_headers)
@@ -396,6 +396,7 @@ def rack_response(status, header)
 
       if NO_CONTENT_CODES.include?(@status)
         header.delete CONTENT_TYPE
+        header.delete 'Content-Length'
         [status, header, []]
       else
         [status, header, RackBody.new(self)]

actionpack/lib/action_dispatch/routing/route_set.rb

@@ -27,8 +27,10 @@ def initialize(raise_on_name_error)
         def dispatcher?; true; end
 
         def serve(req)
-          params = req.path_parameters
-          dispatch(controller(req), params[:action], req)
+          params     = req.path_parameters
+          controller = controller req
+          res        = controller.make_response! req
+          dispatch(controller, params[:action], req, res)
         rescue NameError => e
           if @raise_on_name_error
             raise ActionController::RoutingError, e.message, e.backtrace
@@ -43,8 +45,8 @@ def controller(req)
           req.controller_class
         end
 
-        def dispatch(controller, action, req)
-          controller.dispatch(action, req)
+        def dispatch(controller, action, req, res)
+          controller.dispatch(action, req, res)
         end
       end
 

actionpack/test/abstract_unit.rb

@@ -121,12 +121,16 @@ def self.build_app(routes = nil)
   class DeadEndRoutes < ActionDispatch::Routing::RouteSet
     # Stub Rails dispatcher so it does not get controller references and
     # simply return the controller#action as Rack::Body.
-    class NullController
+    class NullController < ::ActionController::Metal
       def initialize(controller_name)
         @controller = controller_name
       end
 
-      def dispatch(action, req)
+      def make_response!(request)
+        self.class.make_response! request
+      end
+
+      def dispatch(action, req, res)
         [200, {'Content-Type' => 'text/html'}, ["#{@controller}##{action}"]]
       end
     end

actionpack/test/controller/base_test.rb

@@ -93,6 +93,8 @@ def test_no_deprecation_when_action_view_record_identifier_is_included
 class ControllerInstanceTests < ActiveSupport::TestCase
   def setup
     @empty = EmptyController.new
+    @empty.set_request!(ActionDispatch::Request.new({}))
+    @empty.set_response!(EmptyController.make_response!(@empty.request))
     @contained = Submodule::ContainedEmptyController.new
     @empty_controllers = [@empty, @contained]
   end

actionpack/test/controller/new_base/bare_metal_test.rb

@@ -28,6 +28,8 @@ class BareTest < ActiveSupport::TestCase
 
     test "response_body value is wrapped in an array when the value is a String" do
       controller = BareController.new
+      controller.set_request!(ActionDispatch::Request.new({}))
+      controller.set_response!(BareController.make_response!(controller.request))
       controller.index
       assert_equal ["Hello world"], controller.response_body
     end

actionpack/test/controller/new_base/render_html_test.rb

@@ -179,7 +179,7 @@ class RenderHtmlTest < Rack::TestCase
 
     test "rendering from minimal controller returns response with text/html content type" do
       get "/render_html/minimal/index"
-      assert_content_type "text/html"
+      assert_content_type "text/html; charset=utf-8"
     end
 
     test "rendering from normal controller returns response with text/html content type" do

actionpack/test/controller/new_base/render_plain_test.rb

@@ -157,7 +157,7 @@ class RenderPlainTest < Rack::TestCase
 
     test "rendering from minimal controller returns response with text/plain content type" do
       get "/render_plain/minimal/index"
-      assert_content_type "text/plain"
+      assert_content_type "text/plain; charset=utf-8"
     end
 
     test "rendering from normal controller returns response with text/plain content type" do