add strip_attributes

converts empty string to nil on the user model
so unique indexes with null: true will not break

app/models/user.rb

@@ -2,10 +2,10 @@ class User < ActiveRecord::Base
   include UsersHelper
   include ActionView::Helpers
   include Rails.application.routes.url_helpers
+  strip_attributes
 
   belongs_to :role
 
-
   has_secure_password
 
   before_validation :strip_whitespaces, :set_uuid, :set_name, :set_email_token, :set_role