def apply_sorting(self, obj_list, options=None):
        """ override apply_sorting to enable random sorting """
        try:
            return super(CatResource, self).apply_sorting(obj_list, options)
        except InvalidSortError:

            parameter_name = 'order_by'

            if hasattr(options, 'getlist'):
                order_bits = options.getlist(parameter_name)
            else:
                order_bits = options.get(parameter_name)

                if not isinstance(order_bits, (list, tuple)):
                    order_bits = [order_bits]

            for order_by in order_bits:
                order_by_bits = order_by.split(LOOKUP_SEP)

                field_name = order_by_bits[0]

            if field_name == '?':
                return obj_list.order_by(['?'])
            else:
                raise InvalidSortError("The '%s' field does not allow ordering." % field_name)