allows login using username or email

app/models/user.rb

@@ -3,7 +3,8 @@ class User < ActiveRecord::Base
   include Verification
 
   devise :database_authenticatable, :registerable, :confirmable, :recoverable, :rememberable,
-         :trackable, :validatable, :omniauthable, :async, :password_expirable, :secure_validatable
+         :trackable, :validatable, :omniauthable, :async, :password_expirable, :secure_validatable,
+         authentication_keys: [:login]
 
   acts_as_voter
   acts_as_paranoid column: :hidden_at
@@ -48,6 +49,7 @@ class User < ActiveRecord::Base
 
   attr_accessor :skip_password_validation
   attr_accessor :use_redeemable_code
+  attr_accessor :login
 
   scope :administrators, -> { joins(:administrators) }
   scope :moderators,     -> { joins(:moderator) }
@@ -286,6 +288,16 @@ class User < ActiveRecord::Base
   end
   delegate :can?, :cannot?, to: :ability
 
+  # overwritting of Devise method to allow login using email OR username
+  def self.find_for_database_authentication(warden_conditions)
+    conditions = warden_conditions.dup
+    if login = conditions.delete(:login)
+      where(conditions.to_hash).where(["lower(email) = ? OR username = ?", login.downcase, login]).first
+    elsif conditions.has_key?(:username) || conditions.has_key?(:email)
+      where(conditions.to_hash).first
+    end
+  end
+
   private
 
     def clean_document_number

app/views/devise/sessions/new.html.erb

@@ -11,7 +11,7 @@
 <%= form_for(resource, as: resource_name, url: session_path(resource_name)) do |f| %>
   <div class="row">
     <div class="small-12 column">
-      <%= f.email_field :email, autofocus: true, placeholder: t("devise_views.sessions.new.email_label") %>
+      <%= f.text_field :login, autofocus: true, placeholder: t("devise_views.sessions.new.login_label") %>
     </div>
 
     <div class="small-12 column">