add strip_attributes

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

Gemfile

@@ -6,6 +6,7 @@ gem 'mysql2'
 gem 'jquery-rails'
 gem 'bcrypt-ruby' # To use ActiveModel's has_secure_password
 gem 'sanitize'
+gem 'strip_attributes'
 gem 'redcarpet', '~> 3.2.3'
 gem 'hirb' # pretty console output
 gem 'rb-readline'

Gemfile.lock

@@ -165,6 +165,8 @@ GEM
       colorize (>= 0.7.0)
       net-scp (>= 1.1.2)
       net-ssh (>= 2.8.0)
+    strip_attributes (1.5.1)
+      activemodel (>= 3.0, < 5.0)
     thor (0.19.1)
     thread_safe (0.3.3)
     tilt (1.4.1)
@@ -207,6 +209,7 @@ DEPENDENCIES
   rest-client
   sanitize
   sass-rails
+  strip_attributes
   uglifier
   unicorn
   webrick

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

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20150825232749) do
+ActiveRecord::Schema.define(version: 20150826002927) do
 
   create_table "blogposts", force: true do |t|
     t.string   "title"