application_controller.rb not being loaded

In my Rails app (running on rails 2.3.5, ruby 1.8.7), my application_controller.rb file is not being loaded automatically when config.cache_classes = false in environment.rb.

It's in the load path. If I add require 'application_controller' to the end of my environment.rb or set cache_classes = true, then the app works fine.

Why wouldn't it load when classes开发者_如何转开发 are not being cacehed?

This sounds like it for some reason your app is still using 2.3.2 gems for ActiveSupport. It is probably still looking for application.rb, and the undefined pretty_inspect also lends itself to a versioning problem.

First, make sure that you don't have something like this at the top of your environment.rb:

RAILS_GEM_VERSION = '2.3.2'

If you don't, then at the bottom of the your environment.rb find out if something else is setting it wrong by adding this:

puts RAILS_GEM_VERSION

The application code is loaded as part of the Rails::Initializer.run method in environment.rb. It's almost the last step. I know of nothing that would prevent the application controller from loading -- my only suggestion is to make sure there is not a typo in the filename /app/controllers/application_controller.rb and to make sure there is not a typo in the class definition class ApplicationController < ActionController::Base.

I'd like to add that the first part my last comment applies to production mode, where the classes are eager-loaded in Rails::Initializer#load_application_classes, but in development mode it does not cache classes, so loads them as part of a const_missing catcher each request. See ActiveSupport::Dependencies#load_missing_constant.

I have another idea. You mentioned that it is in the load path, but I would confirm later on that it stays in the load path and that a plugin doesn't mess it up or something. At the very bottom of environment.rb (last line) add this line:

puts ActiveSupport::Dependencies.load_paths.pretty_inspect

Then run a script/server from the command line and take a look at the load paths, making sure /path_to_your_rails_app/app/controllers shows up.

The problem is definitely related to config.cache_classes = false; if I switch this to true then the problem disappears.

(Thanks @Ben Lee for leading me towards this)