Cleanup invalid aspects and set unique index

db/migrate/20170813160104_cleanup_aspects_and_add_unique_index.rb

+class CleanupAspectsAndAddUniqueIndex < ActiveRecord::Migration[5.1]
+  class Aspect < ApplicationRecord
+  end
+
+  def up
+    cleanup_aspects
+    add_index :aspects, %i[user_id name], name: :index_aspects_on_user_id_and_name, length: {name: 190}, unique: true
+  end
+
+  def down
+    remove_index :aspects, name: :index_aspects_on_user_id_and_name
+  end
+
+  def cleanup_aspects
+    Aspect.where(user_id: 0).delete_all
+    Aspect.joins("INNER JOIN aspects as a2 ON aspects.user_id = a2.user_id AND aspects.name = a2.name")
+          .where("aspects.id > a2.id").each do |aspect|
+      aspect.update_attributes(name: "#{aspect.name}_#{UUID.generate(:compact)}")
+    end
+  end
+end