Audit and Security event models.

app/models/audit_event.rb

+class AuditEvent < ActiveRecord::Base
+  serialize :details, JSON
+
+  belongs_to :user, foreign_key: :author_id
+
+  validates :author_id, presence: true
+  validates :entity_id, presence: true
+  validates :entity_type, presence: true
+
+  after_initialize :initialize_details
+
+  def initialize_details
+    self.details = {} if details.nil?
+  end
+
+  def author_name
+    self.user.name
+  end
+end

app/models/security_event.rb

+class SecurityEvent < AuditEvent
+end