options_for_migration

# File railties/lib/rails/generators/generated_attribute.rb, line 156
      def options_for_migration
        @attr_options.dup.tap do |options|
          if required?
            options.delete(:required)
            options[:null] = false
          end

          if reference? && !polymorphic?
            options[:foreign_key] = true
          end
        end
      end