Monkey patching Devise (or any Rails gem)

Question

I\'m using the Devise authentication gem in my Rails project, and I want to change the keys it\'s using in flash alerts. (Devise uses :notice and :alert flash keys, but I wa

Answer 1

If you try to reopen a class, it's the same syntax as declaring a new class:

class DeviseController
end

If this code is executed before the real class declaration, it inherits from Object instead of extending the class declared by Devise. Instead I try to use the following

DeviseController.class_eval do
  # Your new methods here
end

This way, you'll get an error if DeviseController has not been declared. As a result, you'll probably end up with

require 'devise/app/controllers/devise_controller'

DeviseController.class_eval do
  # Your new methods here
end

Answer 2

I know this is an old thread but this might still be helpful. You should be able to require the file from the gem directory using the engine called_from path.

  require File.expand_path('../../app/helpers/devise_helper',Devise::Engine.called_from)
  require File.expand_path('../../app/controllers/devise_controller',Devise::Engine.called_from)

  DeviseController.class_eval do
    # Your new methods here
  end

Answer 3

What about adding in the override initializer and alias for the attributes of the flash hash, like this:

class ActionDispatch::Flash::FlashHash
  alias_attribute :success, :notice
  alias_attribute :error, :alert
end

This should allow your application to read flash[:notice] or flash[:success](flash.notice and flash.success)

Answer 4

You need to overwrite DeviseController while keeping around its superclass, in your initializer.

Something like:

class DeviseController < Devise.parent_controller.constantize
    def set_flash_message(key, kind, options = {})
       if key == 'alert'
           key = 'error'
       elsif key == 'notice'
           key = 'success'
       end
       message = find_message(kind, options)
       flash[key] = message if message.present?
    end
end

Answer 5

This is the kind of thing that you will want to put on initialize rails folder, because it's a custom config for this application in particular, second you should use like so:

class DeviseController
    def set_flash_message(key, kind, options = {})
       if key == 'alert'
          key = 'error'
       elsif key == 'notice'
          key = 'success'
       end
       message = find_message(kind, options)
       flash[key] = message if message.present?
    end
end

then you should get the expected behavior. hope it helps since i dont tested, of not pls give a feedback and i will help you try something diferent.

Answer 6

In your initializer file :

module DeviseControllerFlashMessage
  # This method is called when this mixin is included
  def self.included klass
    # klass here is our DeviseController

    klass.class_eval do
      remove_method :set_flash_message
    end
  end

  protected 
  def set_flash_message(key, kind, options = {})
    if key == 'alert'
      key = 'error'
    elsif key == 'notice'
      key = 'success'
    end
    message = find_message(kind, options)
    flash[key] = message if message.present?
  end
end

DeviseController.send(:include, DeviseControllerFlashMessage)

This is pretty brutal but will do what you want. The mixin will delete the previous set_flash_message method forcing the subclasses to fall back to the mixin method.

Edit: self.included is called when the mixin is included in a class. The klass parameter is the Class to which the mixin has been included. In this case, klass is DeviseController, and we call remove_method on it.