class ScreenNameValidator < ActiveModel::EachValidator FORBIDDEN_SCREEN_NAMES = %w(justask_admin retrospring_admin admin justask retrospring support about public notifications inbox sign_in sign_up sidekiq moderation moderator mod administrator siteadmin site_admin help retro_spring retroospring retrosprlng niisding nllsding group settings) def validate_each(record, attribute, value) if FORBIDDEN_SCREEN_NAMES.include? value.downcase record.errors[attribute] << "Thou shalt not use this username! Please choose another one." end end end