Allow users to set/update their display name in LDAP

app/models/user.rb

@@ -1,6 +1,8 @@
 class User < ApplicationRecord
   include EmailValidatable
 
+  attr_accessor :display_name
+
   serialize :preferences, UserPreferences
 
   # Relations
@@ -17,7 +19,7 @@ class User < ApplicationRecord
   has_many :accounts, through: :lndhub_user
 
   validates_uniqueness_of :cn
-  validates_length_of :cn, :minimum => 3
+  validates_length_of :cn, minimum: 3
   validates_format_of :cn, with: /\A([a-z0-9\-])*\z/,
                            if: Proc.new{ |u| u.cn.present? },
                            message: "is invalid. Please use only letters, numbers and -"
@@ -31,6 +33,8 @@ class User < ApplicationRecord
   validates_uniqueness_of :email
   validates :email, email: true
 
+  validates_length_of :display_name, minimum: 3, maximum: 35, allow_blank: true
+
   scope :confirmed, -> { where.not(confirmed_at: nil) }
   scope :pending,   -> { where(confirmed_at: nil) }
 
@@ -115,8 +119,13 @@ class User < ApplicationRecord
     @dn = Devise::LDAP::Adapter.get_dn(self.cn)
   end
 
-  def ldap_entry
-    ldap.fetch_users(uid: self.cn, ou: self.ou).first
+  def ldap_entry(reload: false)
+    return @ldap_entry if defined?(@ldap_entry) && !reload
+    @ldap_entry = ldap.fetch_users(uid: self.cn, ou: self.ou).first
+  end
+
+  def display_name
+    @display_name ||= ldap_entry[:display_name]
   end
 
   def services_enabled