Signup steps with validation

app/models/user.rb

@@ -2,6 +2,10 @@ class User < ApplicationRecord
   # Relations
   has_many :invitations, dependent: :destroy
 
+  validates_uniqueness_of :cn
+  validates_uniqueness_of :email
+  validates_length_of :cn, :minimum => 3
+
   # Include default devise modules. Others available are:
   # :confirmable, :lockable, :timeoutable, :trackable and :omniauthable
   devise :ldap_authenticatable,
@@ -40,4 +44,9 @@ class User < ApplicationRecord
   def address
     "#{self.cn}@#{self.ou}"
   end
+
+  def valid_attribute?(attribute_name)
+    self.valid?
+    self.errors[attribute_name].blank?
+  end
 end