Adding filters to stock Devise controllers

Have some before_filters or after_filters you want to add to some or all of the Devise controller actions without having to subclass all the Devise controllers?

Here's a little trick I use: directly call the before_filter or after_filter class methods in the devise.rb initializer. For example, I have a prepare_for_mobile method that I want to apply as a before_filter to all of the Devise controller actions. This is what I have at the bottom of config/initializers/devise.rb:

	# Add some before filters to all Devise controllers.
	[
	Devise::SessionsController,
	Devise::RegistrationsController,
	Devise::PasswordsController
	].each do |devise_controller_class|
	devise_controller_class.before_filter :prepare_for_mobile
	end

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Note that this is exactly the same as if you had added the before_filter call directly inside these controllers. That means if you wanted to be more selective, you could just as easily do something like:

Devise::RegistrationsController.before_filter :check_for_invite_code, :only => :new

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IMPORTANT NOTE: This tactic only works reliably in the production environment. That is because in development mode, the Devise controller classes get reloaded on each request, but this config file that we've edited does not.

UPDATED 2/16/2012: See my follow-up post where I revisit this issue with a solution that works in both production and development environments.