migration for old roles

db/migrate/20140730104658_migrate_roles_for_cancancan.rb

@@ -0,0 +1,28 @@
+class MigrateRolesForCancancan < ActiveRecord::Migration
+
+  def up
+    # Store the number of existing roles
+    old_roles = Role.count
+
+    Role.all.each do |role|
+      role.users.each do |user|
+        Conference.all.each do |conference|
+          if role.name == 'Admin' || role.name == 'Organizer'
+            user.add_role :organizer, conference
+          else
+            user.add_role role.name.parameterize.underscore.to_sym, conference
+          end
+        end
+      end
+    end
+
+    # Delete old roles
+    Role.first(old_roles).each do |role|
+      role.destroy
+    end
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration.new('Cannot reverse migration. Deleted events cannot be re-created')
+  end
+end