def get_next_sort_string(self, field):
<EOL>if field == self.sort_field:<EOL><INDENT>next_sort = self.toggle_sort_order() + field<EOL><DEDENT>else:<EOL><INDENT>default_order_for_field =self._allowed_sort_fields[field]['<STR_LIT>']<EOL>next_sort = default_order_for_field + field<EOL><DEDENT>return self.get_sort_string(next_sort)<EOL>
If we're already sorted by the field then the sort query
returned reverses the sort order.