pagination.py 文件源码

def decode_cursor(self, request):
        """
        Given a request with a cursor, return a `Cursor` instance.

        Differs from the standard CursorPagination to handle a tuple in the
        position field.
        """
        # Determine if we have a cursor, and if so then decode it.
        encoded = request.query_params.get(self.cursor_query_param)
        if encoded is None:
            return None

        try:
            querystring = b64decode(encoded.encode('ascii')).decode('ascii')
            tokens = urlparse.parse_qs(querystring, keep_blank_values=True)

            offset = tokens.get('o', ['0'])[0]
            # This was hard-coded until Django REST Framework 3.4.0.
            try:
                offset_cutoff = self.offset_cutoff
            except AttributeError:
                offset_cutoff = 1000
            offset = _positive_int(offset, cutoff=offset_cutoff)

            reverse = tokens.get('r', ['0'])[0]
            reverse = bool(int(reverse))

            # The difference. Don't get just the 0th entry: get all entries.
            position = tokens.get('p', None)
        except (TypeError, ValueError):
            raise NotFound(self.invalid_cursor_message)

        return Cursor(offset=offset, reverse=reverse, position=position)