to_sym error on ActionController request

I'm creating a plugin to identify mobile device requests. Any controller that calls is_mobile_aware should have '.html' and '.mobile' templates for all actions. Right now I'm just testing out my code. I'm trying to get every request to use the '.mobile' template, but I'm getting an error when I make requests. Here is the code, with the error below:

Code:

module ActionController
  module MobileAware
    def self.included(base)
      base.extend(ClassMethods)
    end    

    module ClassMethods
      def is_mobile_aware
        include ActionController::MobileAware::InstanceMethods

        before_filter :set_format
      end
    end

    module InstanceMethods
      def set_format        
        request.format = :mobile          
      end
    end
  end
end

Error

undefined method `to_sym' for nil:NilClass

Request

Parameters:

{"format"=>"mobile"}

Thanks for your help!

Full trace:

activesupport (3.0.3) lib/active_support/whiny_nil.rb:48:in `method_missing'
actionpack (3.0.3) lib/action_controller/metal/rendering.rb:10:in `block in process_action'
actionpack (3.0.3) lib/action_controll开发者_开发百科er/metal/rendering.rb:10:in `map'
actionpack (3.0.3) lib/action_controller/metal/rendering.rb:10:in `process_action'
actionpack (3.0.3) lib/abstract_controller/callbacks.rb:18:in `block in process_action'
activesupport (3.0.3) lib/active_support/callbacks.rb:450:in `_run__233835139__process_action__997034143__callbacks'
activesupport (3.0.3) lib/active_support/callbacks.rb:409:in `_run_process_action_callbacks'
activesupport (3.0.3) lib/active_support/callbacks.rb:93:in `run_callbacks'
actionpack (3.0.3) lib/abstract_controller/callbacks.rb:17:in `process_action'
actionpack (3.0.3) lib/action_controller/metal/instrumentation.rb:30:in `block in process_action'
activesupport (3.0.3) lib/active_support/notifications.rb:52:in `block in instrument'
activesupport (3.0.3) lib/active_support/notifications/instrumenter.rb:21:in `instrument'
activesupport (3.0.3) lib/active_support/notifications.rb:52:in `instrument'
actionpack (3.0.3) lib/action_controller/metal/instrumentation.rb:29:in `process_action'
actionpack (3.0.3) lib/action_controller/metal/rescue.rb:17:in `process_action'
actionpack (3.0.3) lib/abstract_controller/base.rb:120:in `process'
actionpack (3.0.3) lib/abstract_controller/rendering.rb:40:in `process'
actionpack (3.0.3) lib/action_controller/metal.rb:138:in `dispatch'
actionpack (3.0.3) lib/action_controller/metal/rack_delegation.rb:14:in `dispatch'
actionpack (3.0.3) lib/action_controller/metal.rb:178:in `block in action'
actionpack (3.0.3) lib/action_dispatch/routing/route_set.rb:62:in `call'
actionpack (3.0.3) lib/action_dispatch/routing/route_set.rb:62:in `dispatch'
actionpack (3.0.3) lib/action_dispatch/routing/route_set.rb:27:in `call'
rack-mount (0.6.13) lib/rack/mount/route_set.rb:148:in `block in call'
rack-mount (0.6.13) lib/rack/mount/code_generation.rb:93:in `block in recognize'
rack-mount (0.6.13) lib/rack/mount/code_generation.rb:75:in `optimized_each'
rack-mount (0.6.13) lib/rack/mount/code_generation.rb:92:in `recognize'
rack-mount (0.6.13) lib/rack/mount/route_set.rb:139:in `call'
actionpack (3.0.3) lib/action_dispatch/routing/route_set.rb:492:in `call'
hoptoad_notifier (2.4.4) lib/hoptoad_notifier/rack.rb:27:in `call'
haml (3.0.25) lib/sass/plugin/rack.rb:41:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/best_standards_support.rb:17:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/head.rb:14:in `call'
rack (1.2.1) lib/rack/methodoverride.rb:24:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/params_parser.rb:21:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/flash.rb:182:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/session/abstract_store.rb:149:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/cookies.rb:295:in `call'
activerecord (3.0.3) lib/active_record/query_cache.rb:32:in `block in call'
activerecord (3.0.3) lib/active_record/connection_adapters/abstract/query_cache.rb:28:in `cache'
activerecord (3.0.3) lib/active_record/query_cache.rb:12:in `cache'
activerecord (3.0.3) lib/active_record/query_cache.rb:31:in `call'
activerecord (3.0.3) lib/active_record/connection_adapters/abstract/connection_pool.rb:353:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/callbacks.rb:46:in `block in call'
activesupport (3.0.3) lib/active_support/callbacks.rb:415:in `_run_call_callbacks'
actionpack (3.0.3) lib/action_dispatch/middleware/callbacks.rb:44:in `call'
rack (1.2.1) lib/rack/sendfile.rb:107:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/remote_ip.rb:48:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/show_exceptions.rb:46:in `call'
railties (3.0.3) lib/rails/rack/logger.rb:13:in `call'
rack (1.2.1) lib/rack/runtime.rb:17:in `call'
activesupport (3.0.3) lib/active_support/cache/strategy/local_cache.rb:72:in `call'
hoptoad_notifier (2.4.4) lib/hoptoad_notifier/user_informer.rb:12:in `call'
rack (1.2.1) lib/rack/lock.rb:11:in `block in call'
:10:in `synchronize'
rack (1.2.1) lib/rack/lock.rb:11:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/static.rb:30:in `call'
railties (3.0.3) lib/rails/application.rb:168:in `call'
railties (3.0.3) lib/rails/application.rb:77:in `method_missing'
railties (3.0.3) lib/rails/rack/log_tailer.rb:14:in `call'
rack (1.2.1) lib/rack/content_length.rb:13:in `call'
rack (1.2.1) lib/rack/handler/webrick.rb:52:in `service'
C:/Ruby192/lib/ruby/1.9.1/webrick/httpserver.rb:111:in `service'
C:/Ruby192/lib/ruby/1.9.1/webrick/httpserver.rb:70:in `run'
C:/Ruby192/lib/ruby/1.9.1/webrick/server.rb:183:in `block in start_thread'