Further digging shows that at the time "actionpack/lib/action_controller/caching/sweeping.rb" is evaluated, the "Sweeper" class can't be defined yet because either ActiveRecord or ActiveRecord::Observer isn't defined yet...

if defined?(ActiveRecord) and defined?(ActiveRecord::Observer)¶
  class Sweeper < ActiveRecord::Observer #:nodoc:¶

If I fire up a "script/console" session, I see "action_controller/caching/sweeping.rb" being immediately evaluated, but ActionController::Caching::Sweeper does not get defined.

If I require "action_controller/caching/sweeping.rb", nothing is evaluated because the file has already been loaded, so "require" does nothing.

If I force re-evaluation of the file by using a different path in my "require", './vendor/rails/actionpack/lib/action_controller/caching/sweeping.rb', for instance, then ActionController::Caching::Sweeper does get defined.

So is there any way to change the load order, so that by the time "sweeping.rb" gets evaluated ActiveRecord and ActiveRecord::Observer are defined?

Looking at this, the "correct" (robust) solution seems to be to:

1. Move the Sweeper class out into a separate file, seeing as it depends on ActiveRecord::Observer.
2. Add an "autoload" line for Sweeper, leaving the existing "autoload" for Sweeping in place.
3. In Sweeper's new file, require ActiveRecord/ActiveRecord::Observer.

Sound ok? If so, I can whip up a patch.

Ok, I now have a relatively minimal test case that demonstrates the problem.

First up, create a new Rails app with a minimal resource:

rails demo
cd demo
script/generate resource foo
rake db:migrate

Set up a sweeper:

echo "class FooSweeper < ActionController::Caching::Sweeper; end" > app/models/foo_sweeper.rb

Add a "cache_sweeper" line and a basic index action to the "app/controllers/foos_controller.rb":

cache_sweeper :foo_sweeper
def index; end

Set up the corresponding view template:

touch app/views/foos/index.html.erb

To actually trigger the issue, I had to install Haml, so add this line to "config/environment.rb":

config.gem 'haml', :version => '2.0.8'

And unpack it (I guess this step is optional):

rake gems:unpack

Now the critical step... add this to "config/environments/development.rb":

Sass::Plugin.options[:always_update] = true
Sass::Plugin.options[:always_check] = true

It doesn't matter what configuration you actually add in there; the important thing is to access the "Sass::Plugin" constant from inside the environment file...

Now start up the server:

script/server

And try hitting a URL like http://localhost:3000/foos

Voila, there's your "Uninitialized constant ActionController::Caching::Sweeper" exception.

I discovered this by printing out a backtrace from within "actionpack/lib/action_controller/caching/sweeping.rb". Here I could see that:

1. The "sweeping.rb" file was evaluated for the first time because the "sass/plugin.rb" file references ActionController
2. At the time "sweeping.rb" is evaluated, ActiveRecord is already defined by ActiveRecord::Observer is not, so the Sweeper class never gets defined

Here's the backtrace:

    /private/tmp/demo/vendor/rails/actionpack/lib/action_controller/caching/sweeping.rb:59
    /private/tmp/demo/vendor/rails/actionpack/lib/action_controller/caching.rb:43:in `included'
    /private/tmp/demo/vendor/rails/actionpack/lib/action_controller/caching.rb:33:in `class_eval'
    /private/tmp/demo/vendor/rails/actionpack/lib/action_controller/caching.rb:33:in `included'
    /private/tmp/demo/vendor/rails/actionpack/lib/action_controller/base.rb:1350:in `include'
    /private/tmp/demo/vendor/rails/actionpack/lib/action_controller/base.rb:1350
    /private/tmp/demo/vendor/rails/actionpack/lib/action_controller/base.rb:1345:in `each'
    /private/tmp/demo/vendor/rails/actionpack/lib/action_controller/base.rb:1345
    /private/tmp/demo/vendor/rails/actionpack/lib/action_controller/base.rb:1344:in `class_eval'
    /private/tmp/demo/vendor/rails/actionpack/lib/action_controller/base.rb:1344
    /private/tmp/demo/vendor/gems/haml-2.0.8/lib/sass/plugin/rails.rb:11
    /Library/Ruby/Site/1.8/rubygems/custom_require.rb:31:in `gem_original_require'
    /Library/Ruby/Site/1.8/rubygems/custom_require.rb:31:in `require'
    /private/tmp/demo/vendor/rails/activesupport/lib/active_support/dependencies.rb:156:in `require'
    /private/tmp/demo/vendor/rails/activesupport/lib/active_support/dependencies.rb:521:in `new_constants_in'
    /private/tmp/demo/vendor/rails/activesupport/lib/active_support/dependencies.rb:156:in `require'
    /private/tmp/demo/vendor/gems/haml-2.0.8/lib/sass/plugin.rb:168
    /private/tmp/demo/vendor/rails/activesupport/lib/active_support/dependencies.rb:380:in `load_without_new_constant_marking'
    /private/tmp/demo/vendor/rails/activesupport/lib/active_support/dependencies.rb:380:in `load_file'
    /private/tmp/demo/vendor/rails/activesupport/lib/active_support/dependencies.rb:521:in `new_constants_in'
    /private/tmp/demo/vendor/rails/activesupport/lib/active_support/dependencies.rb:379:in `load_file'
    /private/tmp/demo/vendor/rails/activesupport/lib/active_support/dependencies.rb:259:in `require_or_load'
    /private/tmp/demo/vendor/rails/activesupport/lib/active_support/dependencies.rb:425:in `load_missing_constant'
    /private/tmp/demo/vendor/rails/activesupport/lib/active_support/dependencies.rb:80:in `const_missing'
    /private/tmp/demo/config/environments/development.rb:21:in `load_environment'
    ./script/../config/../vendor/rails/railties/lib/initializer.rb:356:in `load_environment'
    /private/tmp/demo/vendor/rails/activesupport/lib/active_support/core_ext/kernel/reporting.rb:11:in `silence_warnings'
    ./script/../config/../vendor/rails/railties/lib/initializer.rb:349:in `load_environment'
    ./script/../config/../vendor/rails/railties/lib/initializer.rb:138:in `process'
    ./script/../config/../vendor/rails/railties/lib/initializer.rb:113:in `send'
    ./script/../config/../vendor/rails/railties/lib/initializer.rb:113:in `run'
    /private/tmp/demo/config/environment.rb:9
    /Library/Ruby/Site/1.8/rubygems/custom_require.rb:31:in `gem_original_require'
    /Library/Ruby/Site/1.8/rubygems/custom_require.rb:31:in `require'
    /private/tmp/demo/vendor/rails/activesupport/lib/active_support/dependencies.rb:156:in `require'
    /private/tmp/demo/vendor/rails/activesupport/lib/active_support/dependencies.rb:521:in `new_constants_in'
    /private/tmp/demo/vendor/rails/activesupport/lib/active_support/dependencies.rb:156:in `require'
    /private/tmp/demo/vendor/rails/railties/lib/commands/server.rb:82
    /Library/Ruby/Site/1.8/rubygems/custom_require.rb:31:in `gem_original_require'
    /Library/Ruby/Site/1.8/rubygems/custom_require.rb:31:in `require'
    script/server:3

So one workaround I have available to me is to drop the Sass configuration from my "config/environments/development.rb" file, and instead put it in an initializer in "config/initializers" inside a conditional "if ENV['RAILS_ENV'] == 'development'" block.

But I think a more robust fix might be to make the changes I suggested in my last comment. Like I said, if someone thinks this is a good idea, please let me know and I'll prepare a patch.

I still have this issue. I think Wincent's solution should solve this.

Yes, it would. But...

...So the bug is that since the changes were made to Rails' class caching, and since switching to using "autoload" pervasively, Rails has become a lot more sensitive to certain load-ordering issues.

And it's true that my suggested fix would address this one particular case.

But having said all that, I realized that the way to fix my problem was to move my Sass stuff out of environments/development.rb and into an initializer in config/initializers.

if ENV['RAILS_ENV'] == 'development'
  Sass::Plugin.options[:always_update] = true
  Sass::Plugin.options[:always_check] = true
end

You could argue that it's a bug that Rails has become less tolerant about where it accepts this kind of thing, but I think more than anything it's a documentation bug.

Turns out that this is only the last of several issues that I've run into at startup time since these changes were made to Rails. I've come to the conclusion that pretty much the only thing it is safe to use inside config/environment.rb and config/environments/.rb are "config." statements. Pretty much everything else needs to go in an initializer to avoid this kind of problem.

About the only thing that would have helped me avoid these issues would have been a big warning in the release notes, or a comment in the actual environment files advising that pretty much the only thing that should go in them should be "config.*" statements. I probably only ran into the issue because I was updating an app that was started with a significantly older version of Rails.

It is a bit of a step backwards that you have to put this kind of stuff inside an "if" that explicitly checks RAILS_ENV rather than just sticking it in config/environments/development.rb like you used to. But I doubt anyone is going to be willing to do the work to make all that work again.

I'm still seeing and error with RC2.

=> Rails 2.3.1 application starting on http://0.0.0.0:3000
/Users/chris/workspace/petflight/vendor/rails/activesupport/lib/active_support/dependencies.rb:440:in `load_missing_constant': uninitialized constant ActionController::Caching::Sweeper (NameError)
	from /Users/chris/workspace/petflight/vendor/rails/activesupport/lib/active_support/dependencies.rb:80:in `const_missing'
	from /Users/chris/workspace/petflight/app/sweepers/definition_sweeper.rb:1
	from /Library/Ruby/Site/1.8/rubygems/custom_require.rb:31:in `gem_original_require'
	from /Library/Ruby/Site/1.8/rubygems/custom_require.rb:31:in `require'
	from /Users/chris/workspace/petflight/vendor/rails/activesupport/lib/active_support/dependencies.rb:158:in `require'
	from /Users/chris/workspace/petflight/vendor/rails/activesupport/lib/active_support/dependencies.rb:265:in `require_or_load'
	from /Users/chris/workspace/petflight/vendor/rails/activesupport/lib/active_support/dependencies.rb:425:in `load_missing_constant'
	from /Users/chris/workspace/petflight/vendor/rails/activesupport/lib/active_support/dependencies.rb:80:in `const_missing'
	 ... 26 levels...
	from /Users/chris/workspace/petflight/vendor/rails/railties/lib/commands/server.rb:84
	from /Library/Ruby/Site/1.8/rubygems/custom_require.rb:31:in `gem_original_require'
	from /Library/Ruby/Site/1.8/rubygems/custom_require.rb:31:in `require'
	from ./script/server:3

I'm getting this error as well when using Rails 2.3.2

Here are some more specifics:

if I put this line:

ActionController::Base.cache_store = :file_store, "#{RAILS_ROOT}/tmp/cache"

in either development.rb or in environment.rb then I receive this error:

undefined method cache_sweeper' for Admin::BoardroomsController:Class </code>

However, if I put the cache_store command in an initializer then everything seems to work just fine.

Having this issue as well, can we get this ticket reopened? Should we start a new one?

I had this problem too. A workaround (for the time-being) is to force ActiveRecord to load first in the config. I added a line with ActiveRecord::Base to development/production/test.rb.

rails 2.3.2 has the same problem.

I have this problem in 2.3.2, as well. I haven't troubleshot what's causing it, but adding "ActiveRecord::Base" as the first line of my environment config files does fix it.

If you get this error maybe you are upgrading your app from an older rails version and you should check whats triggering the loading of AR in your environment.rb earlier.

In my case it was lines:

ActionController::Base.logger = Logger.new(STDOUT)
ActionController::Base.logger.level = Logger::INFO
ActiveRecord::Base.logger = Logger.new(STDOUT)
ActiveRecord::Base.logger.level = Logger::INFO

After commenting them everthing was ok.

Very big thanks to W. Colaiuta for defining the problem.

He also has proposed another fix of this issue that will work better with most of the existing rails apps

For me it was:

ActionController::Base.session_options[:domain] = ...

Despite all these tweaks, I still had the problem after upgrading from 2.2.2 to 2.3.2

In config/environnements/development.rb, I had

ActionController::Base.cache_store = :file_store, "#{RAILS_ROOT}/tmp/cache"

After reading the Rails Guides, I found that I could/should write

config.cache_store = :file_store, "#{RAILS_ROOT}/tmp/cache"

And it worked !

In my case I found the culprit to be the cache_store definition, but I think the problem is more about calling ActionController directly and not the cache_store call itself.

I'm sorry, but I'm still having the issue, and don't understand how to solve it. I'm migrating a rails 2.2.3 app to 2.3.2, and since my subdomain cookie don't work any more, I've changed :

ActionController::CgiRequest::DEFAULT_SESSION_OPTIONS.update(:domain => ".mydomain.com")

to

ActionController::Base.session_options[:domain] = ".mydomain.com"

Now I get this famous uninitialized constant ActionController::Caching::Sweeper error. I've tried some of the tips in this ticket without success anyway :(

Thx

You can add these lines to your production.rb, development.rb ....

this is a workaround for problems with loading caching sweepers

ActiveRecord::Base

So you should just load AR:B first.

Update : I've corrected the issue by using :

Rails.configuration.action_controller.session[:domain] = '.staging.mydomain.net'

in my config/environments/staging.rb file.

Ups, a strange formatting.....

The workaround is just to add this line: ActiveRecord::Base In the begging of your production.rb, development.rb ....

@stanislav : thx, what do you mean by adding these line ?

just

ActiveRecord::Base

? I get a NameError: uninitialized constant ActiveRecord error when doing this, I guess I'm doing something wrong :(

Still having this issue when working with Rails 2.3.2.

Even after removing all reference so ActionController direclty within the environment initializers, the sweepers are still not working.

• Application loads successfully
• Caching works as expected
• Sweeper ActiveRecord observers don't seem to be properly hooked into callbacks, as their methods do not get called.

This is when using Rails 2.3.2

I'm running the latest 2-3-stable branch with the above patch included but I'm still seeing the issue.

/Users/Me/MyApp/trunk/vendor/rails/activesupport/lib/active_support/dependencies.rb:440:in `load_missing_constant': uninitialized constant ActionController::Caching::Sweeper (NameError)
	from /Users/Me/MyApp/Code/trunk/vendor/rails/activesupport/lib/active_support/dependencies.rb:80:in `const_missing'
	from /Users/Me/MyApp/Code/trunk/app/sweepers/bank_sweeper.rb:1
	from /Users/Me/MyApp/Code/trunk/vendor/rails/activesupport/lib/active_support/dependencies.rb:380:in `load_without_new_constant_marking'
	from /Users/Me/MyApp/Code/trunk/vendor/rails/activesupport/lib/active_support/dependencies.rb:380:in `load_file'
	from /Users/Me/MyApp/Code/trunk/vendor/rails/activesupport/lib/active_support/dependencies.rb:521:in `new_constants_in'
	from /Users/Me/MyApp/Code/trunk/vendor/rails/activesupport/lib/active_support/dependencies.rb:379:in `load_file'
	from /Users/Me/MyApp/Code/trunk/vendor/rails/activesupport/lib/active_support/dependencies.rb:259:in `require_or_load'
	from /Users/Me/MyApp/Code/trunk/vendor/rails/activesupport/lib/active_support/dependencies.rb:425:in `load_missing_constant'
	 ... 38 levels...
	from /usr/local/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in `require'

Ditto on this error with the most recent 2.3 -- I was not having the issue before, and it seems the most recent commit actually caused it.

Also, action_controller/caching/sweeper.rb has a syntax error -- it's missing an "end". No kidding --

http://github.com/rails/rails/bl...

I can confirm that the patch does not fix the bug on 2.3.2 and no workaround mentioned in this discussion works for me.

Can someone please reopen this ticket. This is very frustrating.

Andreas,

This is fixed in 2-3-stable isn't it?

Just thought I'd point out that it's working for me now

Michael,

I'm still having this issue in Rails 2.3.2. It might be worth noting that the sweeper class is inside a plugin. Some of the reports indicate that the bug depends on the (auto)load order of classes.

The NameError does not occur if I explicitely require the file that defines ActionController::Caching::Sweeper in an initializer, like so:

require "#{RAILS_ROOT}/vendor/rails/actionpack/lib/action_controller/caching/sweeping.rb"

What baffles me is that there is no sweeper.rb file in actionpack-2.3.2/lib/action_controller/caching/. I thought the patch involved moving ActionController::Caching::Sweeper into a separate file.

Andreas,

We're aware of the problem in 2.3.2, however I'm pretty sure it's
fixed in 2-3-stable (a branch in git). If you're able to confirm
that, then I'll know we're good to go and we can release 2.3.3 in a
few days which will include this fix.

Michael,

I'm sorry there was a misunderstanding. I thought the bug was fixed in 2.3.2. I tried 2-3-stable and it works fine.

Thanks for working this out with me :)

I'm looking forward to 2.3.3!