# File lib/data_mapper/constraints/migrations/singleton_methods.rb, line 6
        def auto_migrate!(repository_name = nil)
          auto_migrate_constraints_down(repository_name)
          # TODO: Model#auto_migrate! drops and adds constraints, as well.
          #   is that an avoidable duplication?
          super
          auto_migrate_constraints_up(repository_name)
          self
        end