title: Why rails can't find my sweepers?
body: <p>I have on my controller:</p>
  
  <pre><code>class FormulariosController &lt; ApplicationController
      cache_sweeper :campanha_sweeper, :only =&gt; [:show]
  
      # actions
  end
  </code></pre>
  
  <p>I've tried to create a directory called /sweepers inside app and it didn't work, I've tried inside models to create a /cache folder(there were a blog using this as example) and it didn't work.</p>
  
  <p>My sweeper looks like this:</p>
  
  <pre><code>class CampanhaSweeper &lt; ActionController::Caching::Sweeper
    observe Campanha
  
    def after_update(campanha)
      expire_cache_for(campanha)
    end
  
    private
    def expire_cache_for(campanha)
      expire_page(:controller =&gt; 'formularios', :action =&gt; 'show')
  
      ap "Expired cache for formularios#show in formulariosweeper"
    end
  </code></pre>
  
  <p>end</p>
  
  <p>I get when trying to start the server the following:</p>
  
  <pre><code>/Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/actionpack-3.0.12/lib/action_controller/caching/sweeping.rb:41:in `const_get': uninitialized constant CampanhaSweeper (NameError)
      from /Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/actionpack-3.0.12/lib/action_controller/caching/sweeping.rb:41:in `block in cache_sweeper'
      from /Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/actionpack-3.0.12/lib/action_controller/caching/sweeping.rb:39:in `each'
      from /Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/actionpack-3.0.12/lib/action_controller/caching/sweeping.rb:39:in `cache_sweeper'
      from /Users/thiagomassa/Projects-ginga/ginga-campanhas/app/controllers/formularios_controller.rb:2:in `&lt;class:FormulariosController&gt;'
      from /Users/thiagomassa/Projects-ginga/ginga-campanhas/app/controllers/formularios_controller.rb:1:in `&lt;top (required)&gt;'
      from /Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.0.12/lib/rails/engine.rb:138:in `block (2 levels) in eager_load!'
      from /Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.0.12/lib/rails/engine.rb:137:in `each'
      from /Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.0.12/lib/rails/engine.rb:137:in `block in eager_load!'
      from /Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.0.12/lib/rails/engine.rb:135:in `each'
      from /Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.0.12/lib/rails/engine.rb:135:in `eager_load!'
      from /Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.0.12/lib/rails/application.rb:108:in `eager_load!'
      from /Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.0.12/lib/rails/application/finisher.rb:41:in `block in &lt;module:Finisher&gt;'
      from /Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.0.12/lib/rails/initializable.rb:25:in `instance_exec'
      from /Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.0.12/lib/rails/initializable.rb:25:in `run'
      from /Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.0.12/lib/rails/initializable.rb:50:in `block in run_initializers'
      from /Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.0.12/lib/rails/initializable.rb:49:in `each'
      from /Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.0.12/lib/rails/initializable.rb:49:in `run_initializers'
      from /Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.0.12/lib/rails/application.rb:134:in `initialize!'
      from /Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.0.12/lib/rails/application.rb:77:in `method_missing'
      from /Users/thiagomassa/Projects-ginga/ginga-campanhas/config/environment.rb:5:in `&lt;top (required)&gt;'
      from /Users/thiagomassa/Projects-ginga/ginga-campanhas/config.ru:3:in `block in &lt;main&gt;'
      from /Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/rack-1.2.5/lib/rack/builder.rb:46:in `instance_eval'
      from /Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/rack-1.2.5/lib/rack/builder.rb:46:in `initialize'
      from /Users/thiagomassa/Projects-ginga/ginga-campanhas/config.ru:1:in `new'
      from /Users/thiagomassa/Projects-ginga/ginga-campanhas/config.ru:1:in `&lt;main&gt;'
      from /Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/rack-1.2.5/lib/rack/builder.rb:35:in `eval'
      from /Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/rack-1.2.5/lib/rack/builder.rb:35:in `parse_file'
      from /Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/rack-1.2.5/lib/rack/server.rb:162:in `app'
      from /Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/rack-1.2.5/lib/rack/server.rb:253:in `wrapped_app'
      from /Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/rack-1.2.5/lib/rack/server.rb:204:in `start'
      from /Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.0.12/lib/rails/commands/server.rb:65:in `start'
      from /Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.0.12/lib/rails/commands.rb:30:in `block in &lt;top (required)&gt;'
      from /Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.0.12/lib/rails/commands.rb:27:in `tap'
      from /Users/thiagomassa/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.0.12/lib/rails/commands.rb:27:in `&lt;top (required)&gt;'
      from script/rails:6:in `require'
      from script/rails:6:in `&lt;main&gt;'
  </code></pre>
  
  <p>Why didn't it work? Also, is there any way to expire cache of only a view(of how it's rendered). I'm generating views on the fly and it would be very useful if I could expire the cache of a view that is located at say, views/formularios/a.html.rb</p>
  
  <p>If guys want to know what I'm doing, it's simple. I generate views with forms and when I want to update that view(or it's code) and I'm in production, the view doesn't get updated due to caching so I have to manually reset it's cache everytime I "update" a form.</p>
  
  <p>Thanks.</p>