"Undefined method merge" when using sweeper

Hi,

I'm trying to use sweepers for the first time and got a problem - I get "undefined method `merge' for "/signature/ f2d7c7c66450b169.html":String". The "/signature/f2d7c7c66450b169.html" part of the error message is the cached page.

Here's my sweeper: class FooSweeper < ActionController::Caching::Sweeper   observe Foo

  def after_save(foo)     expire_cache(foo)   end

  def after_destroy(foo)     expire_cache(foo)   end

  def expire_cache(foo)     expire_page signature_path(:opaque_id => foo.opaque_id) # line 13     expire_page signature_image_path(:opaque_id => foo.opaque_id)   end

end

The signature_path(:opaque_id => string) generates "/signature/ string.html" route, so this part works correctly.

Here's stack trace: .../vendor/rails/actionpack/lib/action_controller/caching.rb:125:in `expire_page' .../vendor/rails/actionpack/lib/action_controller/caching.rb:612:in `send' .../vendor/rails/actionpack/lib/action_controller/caching.rb:612:in `method_missing' #{RAILS_ROOT}/app/sweepers/foo_sweeper.rb:13:in `expire_cache' #{RAILS_ROOT}/app/sweepers/foo_sweeper.rb:5:in `after_save' .../app/controllers/foo_controller.rb:61:in `unsubscribe'

Any ideas what can be wrong? I'm using Rails 1.2.6. Thanks in advance

Solved it myself - just changed expire_page to ApplicationController.expire_page. I'm not sure why it didn't work before - I was using Railscast 89 - "Page caching" as the reference.