fix migration. Create dummy user if user doesn't exist, make sure all event_users records are valid

db/migrate/20140801080705_add_users_to_events.rb

@@ -9,16 +9,35 @@ class AddUsersToEvents < ActiveRecord::Migration
 
   class TempEventUser < ActiveRecord::Base
     self.table_name = 'event_users'
+    belongs_to :temp_event
+    belongs_to :temp_user
     attr_accessible :event_id, :user_id, :event_role
   end
 
   def up
     TempEvent.all.each do |event|
-      if TempEventUser.where(event_id: event).blank?
-        # Assign sample user (created in seeds)
-        user = User.find_by(email: 'deleted@localhost.osem')
+      # Create dummy user, if user doesn't exist
+      unless (user = User.find_by(email: 'deleted@localhost.osem'))
+        user = User.new(email: 'deleted@localhost.osem', 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_users = TempEventUser.where(event_id: event)
+      if event_users.blank?
+        # Non existing users for event
         TempEventUser.create!(event_id: event.id, user_id: user.id, event_role: 'submitter')
         TempEventUser.create!(event_id: event.id, user_id: user.id, event_role: 'speaker')
+      else
+        # Wrong records in event_users
+        event_users.each do |eu|
+          unless eu.temp_user.present?
+            eu.user_id = user.id
+            eu.save!
+          end
+        end
       end
     end
   end