use sample user for scheduled events without user

db/migrate/20140717110124_delete_events_without_user.rb

@@ -1,11 +1,40 @@
 class DeleteEventsWithoutUser < ActiveRecord::Migration
-
   def up
     # User deletion without all the proper dependent: :destroy options might have left
     # Events without a submitter (event_user association is deleted, but Event itslef is not)
     Event.all.each do |event|
-      if event.users.blank?
+      if event.submitter.blank? || event.speakers.first.blank?
-        event.destroy
+        if event.start_time.present? # If event is scheduled
+
+          # Create dummy user
+          unless (user = User.find_by(email: 'deleted@localhost.com'))
+            user = User.new(email: 'deleted@localhost.com', name: 'User deleted',
+                                biography: 'Data is no longer available for deleted user.',
+                                password: Devise.friendly_token[0, 20])
+            user.skip_confirmation!
+            user.save!
+          end
+
+          # Event without submitter
+          unless event.event_users.where(event_role: 'submitter').present?
+            event.event_users.create!(user: user, event_role: 'submitter')
+          end
+
+          # Event without speaker
+          unless event.event_users.where(event_role: 'speaker').present?
+            event.event_users.create!(user: user, event_role: 'speaker')
+          end
+
+          event.event_users.each do |eu|
+           unless eu.user.present?
+             eu.user = user
+             eu.save!
+           end
+          end
+
+        else
+          event.destroy
+        end
       end
     end
   end