Use concerns to keep your models manageable

application_controller.rb

class WmsWebCma::ApplicationController < ActionController::Base
  protect_from_forgery

  before_filter :set_locale

  helper_method :current_agent, :company_branding

  def current_agent
    @current_agent ||= (session[:current_agent] ? Agent.find(session[:current_agent]["uuid"]) : nil)
  end

  def company_branding
    @company_branding ||= WmsWebCma::Branding.company(agent_uuid: agent_uuid_for_branding) if current_agent
  end

  def logged_in?
    current_agent
  end

  def has_subscription?
    warn current_agent.subscription('webcma').inspect if current_agent
    @has_subscription ||= current_agent && current_agent.subscription('webcma').try(:valid)
  end

  def has_mld_id?
    @has_mld_id ||= current_agent && current_agent.mls_agentid.present?
  end

  def render_unauthorized(message = "")
    @message = message
    render :template => "wms_web_cma/errors/unauthorized", :status => :unauthorized
    return false
  end

  def render_no_mls
    render :template => "wms_web_cma/errors/no_mls", :status => :unauthorized
    return false
  end

  protected
  def agent_uuid_for_branding
    if params[:brand_as].present?
      agent_uuid = params[:brand_as]
    else
      agent_uuid = current_agent.uuid
    end
    agent_uuid
  end

  private
  def set_locale
    I18n.locale = params[:locale] if params[:locale].present?
  end

  def default_url_options(options = {})
    {locale: I18n.locale}
  end
end

gistfile1.rb

# autoload concerns
module YourApp
  class Application < Rails::Application
    config.autoload_paths += %W(
      #{config.root}/app/controllers/concerns
      #{config.root}/app/models/concerns
    )
  end
end

# app/models/concerns/trashable.rb
module Trashable
  extend ActiveSupport::Concern
  
  included do
    default_scope   where(trashed: false)
    scope :trashed, where(trashed: true)
  end
  
  def trash
    update_attribute :trashed, true
  end
end

# app/models/message.rb
class Message < ActiveRecord::Base
  include Trashable, Subscribable, Commentable, Eventable
end