Rails 4 + Devise Login with email or username and strong parameters

I'm new to RoR and stuck with this devise problem. I want to allow users to sign in with email OR username (registration with username is already ok). I followed these articles: Article 1 and Article 2 and you can see the result below: application_controller.rb ``` class ApplicationController < ActionController::Base protect_from_forgery with: :exception before_filter :configure_permitted_parameters, if: :devise_controller? protected def configure_permitted_parameters devise_parameter_sanitizer.for(:sign_up) { |u| u.permit(:username, :email, :password) } devise_parameter_sanitizer.for(:sign_in) { |u| u.permit(:login, :password, :remember_me) } end end ``` user.rb ``` class User < ActiveRecord::Base devise :database_authenticatable, :registerable, :recoverable, :rememberable, :trackable, :validatable, :authentication_keys => [:login] validates_uniqueness_of :username validates_presence_of :username validates :username, length: { in: 4..20 } def self.find_first_by_auth_conditions(warden_conditions) conditions = warden_conditions.dup if login = conditions.delete(:login) where(conditions).where(["lower(username) = :value OR lower(email) = :value", { :value => login.downcase }]).first else where(conditions).first end end end ``` new.html.erb ``` <%= form_for(resource, :as => resource_name, :url => session_path(resource_name)) do |f| %> <div><%= f.label :login, "Pseudo ou email" %><br /> <%= f.text_field :login, :autofocus => true %></div> ... ``` devise.rb ... config.authentication_keys = [ :login ] ... result ``` Showing /home/action/workspace/rchq/app/views/devise/sessions/new.html.erb where line #5 raised: undefined method `login' for #<User:0x000000033996a0> ``` I don't understand why it doesn't work because I specified that for "sign_in" permit :login for User.