pull the flash methods in to their own module

We only want to activate flash when the user has enabled it.  Api
servers don't use flash, so add an empty implementation to the base
Request object.

actionpack/lib/action_dispatch/http/request.rb

@@ -384,6 +384,9 @@ def logger
       get_header("action_dispatch.logger".freeze)
     end
 
+    def commit_flash
+    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/flash.rb

@@ -1,40 +1,6 @@
 require 'active_support/core_ext/hash/keys'
 
 module ActionDispatch
-  class Request
-    # Access the contents of the flash. Use <tt>flash["notice"]</tt> to
-    # read a notice you put there or <tt>flash["notice"] = "hello"</tt>
-    # to put a new one.
-    def flash
-      flash = flash_hash
-      return flash if flash
-      self.flash = Flash::FlashHash.from_session_value(session["flash"])
-    end
-
-    def flash=(flash)
-      set_header Flash::KEY, flash
-    end
-
-    def flash_hash # :nodoc:
-      get_header Flash::KEY
-    end
-
-    def commit_flash # :nodoc:
-      session    = self.session || {}
-      flash_hash = self.flash_hash
-
-      if flash_hash && (flash_hash.present? || session.key?('flash'))
-        session["flash"] = flash_hash.to_session_value
-        self.flash = flash_hash.dup
-      end
-
-      if (!session.respond_to?(:loaded?) || session.loaded?) && # (reset_session uses {}, which doesn't implement #loaded?)
-        session.key?('flash') && session['flash'].nil?
-        session.delete('flash')
-      end
-    end
-  end
-
   # The flash provides a way to pass temporary primitive-types (String, Array, Hash) between actions. Anything you place in the flash will be exposed
   # to the very next action and then cleared out. This is a great way of doing notices and alerts, such as a create
   # action that sets <tt>flash[:notice] = "Post successfully created"</tt> before redirecting to a display action that can
@@ -72,6 +38,40 @@ def commit_flash # :nodoc:
   class Flash
     KEY = 'action_dispatch.request.flash_hash'.freeze
 
+    module RequestMethods
+      # Access the contents of the flash. Use <tt>flash["notice"]</tt> to
+      # read a notice you put there or <tt>flash["notice"] = "hello"</tt>
+      # to put a new one.
+      def flash
+        flash = flash_hash
+        return flash if flash
+        self.flash = Flash::FlashHash.from_session_value(session["flash"])
+      end
+
+      def flash=(flash)
+        set_header Flash::KEY, flash
+      end
+
+      def flash_hash # :nodoc:
+        get_header Flash::KEY
+      end
+
+      def commit_flash # :nodoc:
+        session    = self.session || {}
+        flash_hash = self.flash_hash
+
+        if flash_hash && (flash_hash.present? || session.key?('flash'))
+          session["flash"] = flash_hash.to_session_value
+          self.flash = flash_hash.dup
+        end
+
+        if (!session.respond_to?(:loaded?) || session.loaded?) && # (reset_session uses {}, which doesn't implement #loaded?)
+            session.key?('flash') && session['flash'].nil?
+          session.delete('flash')
+        end
+      end
+    end
+
     class FlashNow #:nodoc:
       attr_accessor :flash
 
@@ -285,4 +285,8 @@ def stringify_array(array)
 
     def self.new(app) app; end
   end
+
+  class Request
+    prepend Flash::RequestMethods
+  end
 end