handlers.py 文件源码

def head(self):
        """
        Handles HEAD request.

        1. Validates GET parameters using GET input schema and validator.
        2. Fetches total amount of items and returns it in X-Total header.
        3. Finishes response.

        :raises: In case of bad query parameters - HTTPError 400.
        """
        await self.validate({k: self.get_argument(k) for k in self.request.query_arguments.keys()},
                            self.get_schema_input)
        try:
            qs = self.get_queryset(paginate=False)
        except AttributeError as e:
            # Wrong field name in filter or order_by
            # Request.body is not available in HEAD request
            # No detail info will be provided
            raise HTTPError(400)
        try:
            total_num = await self.application.objects.count(qs)
        except (peewee.DataError, peewee.ProgrammingError, ValueError) as e:
            # Bad parameters
            # Request.body is not available in HEAD request
            # No detail info will be provided
            raise HTTPError(400)
        self.set_header('X-Total', total_num)
        self.finish()