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 = parse.parse_qs(querystring, keep_blank_values=True)
offset = tokens.get('o', ['0'])[0]
offset = _positive_int(offset, cutoff=self.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)
def decode_cursor(self, request):
"""
Given a request with a cursor, return a `Cursor` instance.
"""
# 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
# The offset in the cursor is used in situations where we have a
# nearly-unique index. (Eg millisecond precision creation timestamps)
# We guard against malicious users attempting to cause expensive database
# queries, by having a hard cap on the maximum possible size of the offset.
OFFSET_CUTOFF = getattr(settings, 'CURSOR_PAGINATION_OFFSET_CUTOFF',
1000)
try:
querystring = b64decode(encoded.encode('ascii')).decode('ascii')
tokens = parse_qs(querystring, keep_blank_values=True)
offset = tokens.get('o', ['0'])[0]
offset = _positive_int(offset, cutoff=OFFSET_CUTOFF)
reverse = tokens.get('r', ['0'])[0]
reverse = bool(int(reverse))
position = tokens.get('p', [None])[0]
except (TypeError, ValueError):
raise NotFound(self.invalid_cursor_message)
return Cursor(offset=offset, reverse=reverse, position=position)
def decode_cursor(self, request):
"""
Given a request with a cursor, return a `Cursor` instance.
"""
# 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:
reverse = False
if encoded.startswith('-'):
encoded = encoded[1:]
reverse = True
offset = 0
parts = encoded.split('+', 1)
if '-' in parts[0]:
position = parts[0]
else:
position = None
if len(parts) > 1:
offset = _positive_int(parts[1], cutoff=self.offset_cutoff)
except (TypeError, ValueError):
raise NotFound(self.invalid_cursor_message)
return Cursor(offset=offset, reverse=reverse, position=position)
def get_next_link(self):
if not self.has_next:
return None
offset = self.page_size if not self.has_previous else self.cursor.offset + self.page_size
cursor = Cursor(offset=offset, reverse=False, position=None)
return self.encode_cursor(cursor)
def get_previous_link(self):
if not self.has_previous:
return None
offset = self.cursor.offset - self.page_size
if offset < 0:
offset = 0
cursor = Cursor(offset=offset, reverse=False, position=None)
return self.encode_cursor(cursor)
def decode_cursor(self, request):
bucket = self._context.get('bucket')
key_marker = self.get_key_marker(request)
position = None
if key_marker:
try:
upload = MultipartUploadManager().get_multipart_upload_delete_invalid(bucket=bucket, obj_path=key_marker)
except exceptions.S3Error as e:
raise e
if upload:
position = upload.create_time
else:
upload_id_marker = self.get_upload_id_marker(request)
if upload_id_marker:
position = get_datetime_from_upload_id(upload_id_marker)
else:
raise exceptions.S3NoSuchUpload('key-marker upload not found.')
return Cursor(offset=0, reverse=False, position=position)
def _get_start_after_cursor(self, start_after):
"""
获取分页起始参数start_after对应的游标cursor
:param start_after: 对象Key
:return:
Cursor() or None
:raises: S3Error
"""
hm = HarborManager()
bucket = self._context.get('bucket', None)
if not bucket:
bucket_name = self._context('bucket_name')
bucket = hm.get_bucket(bucket_name=bucket_name)
if not bucket:
return None
table_name = bucket.get_bucket_table_name()
try:
obj = HarborManager().get_metadata_obj(table_name=table_name, path=start_after)
except exceptions.S3Error as e:
raise e
if not obj:
raise exceptions.S3NoSuchKey(_('无效的参数start_after'))
order = self.ordering[0]
is_reversed = order.startswith('-')
attr = obj.id # order by id
if is_reversed: # 倒序
position = max(attr - 1, 0)
reverse = False
else:
position = attr + 1
reverse = True
return Cursor(offset=0, reverse=reverse, position=position)
def decode_cursor(self, request):
key_marker = self.get_key_marker(request)
position = key_marker if key_marker else None
return Cursor(offset=0, reverse=False, position=position)