Activate sweeper AR callback only in context of the configured controller actions

lib/rails/observers/action_controller/caching/sweeper.rb

@@ -27,6 +27,14 @@ def around(controller)
         clean_up
       end
 
+      # Execute standard observer logic only if controller was initiated, i.e.
+      # it is being triggered from the controller/action as specified in
+      # controller's <tt>cache_sweeper</tt> class method.
+      def update(observed_method, object, *extra_args, &block) #:nodoc:
+        return unless controller
+        super
+      end
+
       protected
       # gets the action cache path for the given options.
       def action_path_for(options)
@@ -48,8 +56,15 @@ def callback(timing)
         controller_callback_method_name = "#{timing}_#{controller.controller_name.underscore}"
         action_callback_method_name     = "#{controller_callback_method_name}_#{controller.action_name}"
 
-        __send__(controller_callback_method_name) if respond_to?(controller_callback_method_name, true)
-        __send__(action_callback_method_name)     if respond_to?(action_callback_method_name, true)
+        if respond_to?(controller_callback_method_name, true)
+          warn "[DEPRECATION] Using Sweeper for controller callback is deprecated. Sweeper is just an observer of ActiveRecord object that gets triggered when specified controller action is executed"
+          __send__(controller_callback_method_name)
+        end
+
+        if respond_to?(action_callback_method_name, true)
+          warn "[DEPRECATION] Using Sweeper for controller callback is deprecated. Sweeper is just an observer of ActiveRecord object that gets triggered when specified controller action is executed"
+          __send__(action_callback_method_name)
+        end
       end
 
       def method_missing(method, *arguments, &block)

lib/rails/observers/action_controller/caching/sweeping.rb

@@ -1,7 +1,9 @@
 module ActionController #:nodoc:
   module Caching
     # Sweepers are the terminators of the caching world and responsible for expiring caches when model objects change.
-    # They do this by being half-observers, half-filters and implementing callbacks for both roles. A Sweeper example:
+    # They do this by being observers of model that are executed only when specified controller action is being executed.
+    # Sweeper can access the corresponding controller via <tt>controller</tt> accessor. Additionally, missing method calls are automatically routed to the corresponding controller.
+    # A Sweeper example:
     #
     #   class ListSweeper < ActionController::Caching::Sweeper
     #     observe List, Item
@@ -21,7 +23,7 @@ module Caching
     #     cache_sweeper :list_sweeper, :only => [ :edit, :destroy, :share ]
     #   end
     #
-    # In the example above, four actions are cached and three actions are responsible for expiring those caches.
+    # In the example above, four actions are cached and three actions are responsible for expiring those caches, i.e. <tt>ListSweeper.after_save</tt> will only be executed in the context of those actions.
     #
     # You can also name an explicit class in the declaration of a sweeper, which is needed if the sweeper is in a module:
     #

test/sweeper_test.rb

@@ -6,7 +6,13 @@
 
 SharedTestRoutes = ActionDispatch::Routing::RouteSet.new
 
-class AppSweeper < ActionController::Caching::Sweeper; end
+class AppSweeper < ActionController::Caching::Sweeper
+
+  def around_save(record)
+    yield :in_around_save
+  end
+
+end
 
 class SweeperTestController < ActionController::Base
   include SharedTestRoutes.url_helpers
@@ -40,6 +46,25 @@ def test_sweeper_should_not_ignore_no_method_error
     end
   end
 
+  def test_sweeper_should_not_respond_to_update_if_controller_is_not_set
+    sweeper = AppSweeper.send(:new)
+    yielded_value = nil
+    sweeper.update(:around_save, Object.new) do |val|
+      yielded_value = val
+    end
+    assert_nil yielded_value
+  end
+
+  def test_sweeper_should_respond_to_update_if_controller_is_set
+    sweeper = AppSweeper.send(:new)
+    sweeper.controller = SweeperTestController.new
+    yielded_value = nil
+    sweeper.update(:around_save, Object.new) do |val|
+      yielded_value = val
+    end
+    assert_equal :in_around_save, yielded_value
+  end
+
   def test_sweeper_should_not_block_rendering
     response = test_process(SweeperTestController)
     assert_equal 'hello world', response.body