# Copyright 2009-present MongoDB, Inc. # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. """Tools for representing files stored in GridFS.""" import datetime import io import math import os from typing import Any, Iterable, List, Mapping, NoReturn, Optional from bson.binary import Binary from bson.int64 import Int64 from bson.objectid import ObjectId from bson.son import SON from gridfs.errors import CorruptGridFile, FileExists, NoFile from pymongo import ASCENDING from pymongo.client_session import ClientSession from pymongo.collection import Collection from pymongo.cursor import Cursor from pymongo.errors import ( ConfigurationError, CursorNotFound, DuplicateKeyError, InvalidOperation, OperationFailure, ) from pymongo.read_preferences import ReadPreference _SEEK_SET = os.SEEK_SET _SEEK_CUR = os.SEEK_CUR _SEEK_END = os.SEEK_END EMPTY = b"" NEWLN = b"\n" """Default chunk size, in bytes.""" # Slightly under a power of 2, to work well with server's record allocations. DEFAULT_CHUNK_SIZE = 255 * 1024 _C_INDEX: SON[str, Any] = SON([("files_id", ASCENDING), ("n", ASCENDING)]) _F_INDEX: SON[str, Any] = SON([("filename", ASCENDING), ("uploadDate", ASCENDING)]) def _grid_in_property( field_name: str, docstring: str, read_only: Optional[bool] = False, closed_only: Optional[bool] = False, ) -> Any: """Create a GridIn property.""" def getter(self: Any) -> Any: if closed_only and not self._closed: raise AttributeError("can only get %r on a closed file" % field_name) # Protect against PHP-237 if field_name == "length": return self._file.get(field_name, 0) return self._file.get(field_name, None) def setter(self: Any, value: Any) -> Any: if self._closed: self._coll.files.update_one({"_id": self._file["_id"]}, {"$set": {field_name: value}}) self._file[field_name] = value if read_only: docstring += "\n\nThis attribute is read-only." elif closed_only: docstring = "%s\n\n%s" % ( docstring, "This attribute is read-only and " "can only be read after :meth:`close` " "has been called.", ) if not read_only and not closed_only: return property(getter, setter, doc=docstring) return property(getter, doc=docstring) def _grid_out_property(field_name: str, docstring: str) -> Any: """Create a GridOut property.""" def getter(self: Any) -> Any: self._ensure_file() # Protect against PHP-237 if field_name == "length": return self._file.get(field_name, 0) return self._file.get(field_name, None) docstring += "\n\nThis attribute is read-only." return property(getter, doc=docstring) def _clear_entity_type_registry(entity: Any, **kwargs: Any) -> Any: """Clear the given database/collection object's type registry.""" codecopts = entity.codec_options.with_options(type_registry=None) return entity.with_options(codec_options=codecopts, **kwargs) def _disallow_transactions(session: Optional[ClientSession]) -> None: if session and session.in_transaction: raise InvalidOperation("GridFS does not support multi-document transactions") class GridIn(object): """Class to write data to GridFS.""" def __init__( self, root_collection: Collection, session: Optional[ClientSession] = None, **kwargs: Any ) -> None: """Write a file to GridFS Application developers should generally not need to instantiate this class directly - instead see the methods provided by :class:`~gridfs.GridFS`. Raises :class:`TypeError` if `root_collection` is not an instance of :class:`~pymongo.collection.Collection`. Any of the file level options specified in the `GridFS Spec `_ may be passed as keyword arguments. Any additional keyword arguments will be set as additional fields on the file document. Valid keyword arguments include: - ``"_id"``: unique ID for this file (default: :class:`~bson.objectid.ObjectId`) - this ``"_id"`` must not have already been used for another file - ``"filename"``: human name for the file - ``"contentType"`` or ``"content_type"``: valid mime-type for the file - ``"chunkSize"`` or ``"chunk_size"``: size of each of the chunks, in bytes (default: 255 kb) - ``"encoding"``: encoding used for this file. Any :class:`str` that is written to the file will be converted to :class:`bytes`. :Parameters: - `root_collection`: root collection to write to - `session` (optional): a :class:`~pymongo.client_session.ClientSession` to use for all commands - `**kwargs: Any` (optional): file level options (see above) .. versionchanged:: 4.0 Removed the `disable_md5` parameter. See :ref:`removed-gridfs-checksum` for details. .. versionchanged:: 3.7 Added the `disable_md5` parameter. .. versionchanged:: 3.6 Added ``session`` parameter. .. versionchanged:: 3.0 `root_collection` must use an acknowledged :attr:`~pymongo.collection.Collection.write_concern` """ if not isinstance(root_collection, Collection): raise TypeError("root_collection must be an instance of Collection") if not root_collection.write_concern.acknowledged: raise ConfigurationError("root_collection must use acknowledged write_concern") _disallow_transactions(session) # Handle alternative naming if "content_type" in kwargs: kwargs["contentType"] = kwargs.pop("content_type") if "chunk_size" in kwargs: kwargs["chunkSize"] = kwargs.pop("chunk_size") coll = _clear_entity_type_registry(root_collection, read_preference=ReadPreference.PRIMARY) # Defaults kwargs["_id"] = kwargs.get("_id", ObjectId()) kwargs["chunkSize"] = kwargs.get("chunkSize", DEFAULT_CHUNK_SIZE) object.__setattr__(self, "_session", session) object.__setattr__(self, "_coll", coll) object.__setattr__(self, "_chunks", coll.chunks) object.__setattr__(self, "_file", kwargs) object.__setattr__(self, "_buffer", io.BytesIO()) object.__setattr__(self, "_position", 0) object.__setattr__(self, "_chunk_number", 0) object.__setattr__(self, "_closed", False) object.__setattr__(self, "_ensured_index", False) def __create_index(self, collection: Collection, index_key: Any, unique: bool) -> None: doc = collection.find_one(projection={"_id": 1}, session=self._session) if doc is None: try: index_keys = [ index_spec["key"] for index_spec in collection.list_indexes(session=self._session) ] except OperationFailure: index_keys = [] if index_key not in index_keys: collection.create_index(index_key.items(), unique=unique, session=self._session) def __ensure_indexes(self) -> None: if not object.__getattribute__(self, "_ensured_index"): _disallow_transactions(self._session) self.__create_index(self._coll.files, _F_INDEX, False) self.__create_index(self._coll.chunks, _C_INDEX, True) object.__setattr__(self, "_ensured_index", True) def abort(self) -> None: """Remove all chunks/files that may have been uploaded and close.""" self._coll.chunks.delete_many({"files_id": self._file["_id"]}, session=self._session) self._coll.files.delete_one({"_id": self._file["_id"]}, session=self._session) object.__setattr__(self, "_closed", True) @property def closed(self) -> bool: """Is this file closed?""" return self._closed _id: Any = _grid_in_property("_id", "The ``'_id'`` value for this file.", read_only=True) filename: Optional[str] = _grid_in_property("filename", "Name of this file.") name: Optional[str] = _grid_in_property("filename", "Alias for `filename`.") content_type: Optional[str] = _grid_in_property("contentType", "Mime-type for this file.") length: int = _grid_in_property("length", "Length (in bytes) of this file.", closed_only=True) chunk_size: int = _grid_in_property("chunkSize", "Chunk size for this file.", read_only=True) upload_date: datetime.datetime = _grid_in_property( "uploadDate", "Date that this file was uploaded.", closed_only=True ) md5: Optional[str] = _grid_in_property( "md5", "MD5 of the contents of this file if an md5 sum was created.", closed_only=True ) _buffer: io.BytesIO _closed: bool def __getattr__(self, name: str) -> Any: if name in self._file: return self._file[name] raise AttributeError("GridIn object has no attribute '%s'" % name) def __setattr__(self, name: str, value: Any) -> None: # For properties of this instance like _buffer, or descriptors set on # the class like filename, use regular __setattr__ if name in self.__dict__ or name in self.__class__.__dict__: object.__setattr__(self, name, value) else: # All other attributes are part of the document in db.fs.files. # Store them to be sent to server on close() or if closed, send # them now. self._file[name] = value if self._closed: self._coll.files.update_one({"_id": self._file["_id"]}, {"$set": {name: value}}) def __flush_data(self, data: Any) -> None: """Flush `data` to a chunk.""" self.__ensure_indexes() if not data: return assert len(data) <= self.chunk_size chunk = {"files_id": self._file["_id"], "n": self._chunk_number, "data": Binary(data)} try: self._chunks.insert_one(chunk, session=self._session) except DuplicateKeyError: self._raise_file_exists(self._file["_id"]) self._chunk_number += 1 self._position += len(data) def __flush_buffer(self) -> None: """Flush the buffer contents out to a chunk.""" self.__flush_data(self._buffer.getvalue()) self._buffer.close() self._buffer = io.BytesIO() def __flush(self) -> Any: """Flush the file to the database.""" try: self.__flush_buffer() # The GridFS spec says length SHOULD be an Int64. self._file["length"] = Int64(self._position) self._file["uploadDate"] = datetime.datetime.utcnow() return self._coll.files.insert_one(self._file, session=self._session) except DuplicateKeyError: self._raise_file_exists(self._id) def _raise_file_exists(self, file_id: Any) -> NoReturn: """Raise a FileExists exception for the given file_id.""" raise FileExists("file with _id %r already exists" % file_id) def close(self) -> None: """Flush the file and close it. A closed file cannot be written any more. Calling :meth:`close` more than once is allowed. """ if not self._closed: self.__flush() object.__setattr__(self, "_closed", True) def read(self, size: int = -1) -> NoReturn: raise io.UnsupportedOperation("read") def readable(self) -> bool: return False def seekable(self) -> bool: return False def write(self, data: Any) -> None: """Write data to the file. There is no return value. `data` can be either a string of bytes or a file-like object (implementing :meth:`read`). If the file has an :attr:`encoding` attribute, `data` can also be a :class:`str` instance, which will be encoded as :attr:`encoding` before being written. Due to buffering, the data may not actually be written to the database until the :meth:`close` method is called. Raises :class:`ValueError` if this file is already closed. Raises :class:`TypeError` if `data` is not an instance of :class:`bytes`, a file-like object, or an instance of :class:`str`. Unicode data is only allowed if the file has an :attr:`encoding` attribute. :Parameters: - `data`: string of bytes or file-like object to be written to the file """ if self._closed: raise ValueError("cannot write to a closed file") try: # file-like read = data.read except AttributeError: # string if not isinstance(data, (str, bytes)): raise TypeError("can only write strings or file-like objects") if isinstance(data, str): try: data = data.encode(self.encoding) except AttributeError: raise TypeError("must specify an encoding for file in order to write str") read = io.BytesIO(data).read if self._buffer.tell() > 0: # Make sure to flush only when _buffer is complete space = self.chunk_size - self._buffer.tell() if space: try: to_write = read(space) except BaseException: self.abort() raise self._buffer.write(to_write) if len(to_write) < space: return # EOF or incomplete self.__flush_buffer() to_write = read(self.chunk_size) while to_write and len(to_write) == self.chunk_size: self.__flush_data(to_write) to_write = read(self.chunk_size) self._buffer.write(to_write) def writelines(self, sequence: Iterable[Any]) -> None: """Write a sequence of strings to the file. Does not add seperators. """ for line in sequence: self.write(line) def writeable(self) -> bool: return True def __enter__(self) -> "GridIn": """Support for the context manager protocol.""" return self def __exit__(self, exc_type: Any, exc_val: Any, exc_tb: Any) -> Any: """Support for the context manager protocol. Close the file if no exceptions occur and allow exceptions to propagate. """ if exc_type is None: # No exceptions happened. self.close() else: # Something happened, at minimum mark as closed. object.__setattr__(self, "_closed", True) # propagate exceptions return False class GridOut(io.IOBase): """Class to read data out of GridFS.""" def __init__( self, root_collection: Collection, file_id: Optional[int] = None, file_document: Optional[Any] = None, session: Optional[ClientSession] = None, ) -> None: """Read a file from GridFS Application developers should generally not need to instantiate this class directly - instead see the methods provided by :class:`~gridfs.GridFS`. Either `file_id` or `file_document` must be specified, `file_document` will be given priority if present. Raises :class:`TypeError` if `root_collection` is not an instance of :class:`~pymongo.collection.Collection`. :Parameters: - `root_collection`: root collection to read from - `file_id` (optional): value of ``"_id"`` for the file to read - `file_document` (optional): file document from `root_collection.files` - `session` (optional): a :class:`~pymongo.client_session.ClientSession` to use for all commands .. versionchanged:: 3.8 For better performance and to better follow the GridFS spec, :class:`GridOut` now uses a single cursor to read all the chunks in the file. .. versionchanged:: 3.6 Added ``session`` parameter. .. versionchanged:: 3.0 Creating a GridOut does not immediately retrieve the file metadata from the server. Metadata is fetched when first needed. """ if not isinstance(root_collection, Collection): raise TypeError("root_collection must be an instance of Collection") _disallow_transactions(session) root_collection = _clear_entity_type_registry(root_collection) super().__init__() self.__chunks = root_collection.chunks self.__files = root_collection.files self.__file_id = file_id self.__buffer = EMPTY self.__chunk_iter = None self.__position = 0 self._file = file_document self._session = session _id: Any = _grid_out_property("_id", "The ``'_id'`` value for this file.") filename: str = _grid_out_property("filename", "Name of this file.") name: str = _grid_out_property("filename", "Alias for `filename`.") content_type: Optional[str] = _grid_out_property("contentType", "Mime-type for this file.") length: int = _grid_out_property("length", "Length (in bytes) of this file.") chunk_size: int = _grid_out_property("chunkSize", "Chunk size for this file.") upload_date: datetime.datetime = _grid_out_property( "uploadDate", "Date that this file was first uploaded." ) aliases: Optional[List[str]] = _grid_out_property("aliases", "List of aliases for this file.") metadata: Optional[Mapping[str, Any]] = _grid_out_property( "metadata", "Metadata attached to this file." ) md5: Optional[str] = _grid_out_property( "md5", "MD5 of the contents of this file if an md5 sum was created." ) _file: Any __chunk_iter: Any def _ensure_file(self) -> None: if not self._file: _disallow_transactions(self._session) self._file = self.__files.find_one({"_id": self.__file_id}, session=self._session) if not self._file: raise NoFile( "no file in gridfs collection %r with _id %r" % (self.__files, self.__file_id) ) def __getattr__(self, name: str) -> Any: self._ensure_file() if name in self._file: return self._file[name] raise AttributeError("GridOut object has no attribute '%s'" % name) def readable(self) -> bool: return True def readchunk(self) -> bytes: """Reads a chunk at a time. If the current position is within a chunk the remainder of the chunk is returned. """ received = len(self.__buffer) chunk_data = EMPTY chunk_size = int(self.chunk_size) if received > 0: chunk_data = self.__buffer elif self.__position < int(self.length): chunk_number = int((received + self.__position) / chunk_size) if self.__chunk_iter is None: self.__chunk_iter = _GridOutChunkIterator( self, self.__chunks, self._session, chunk_number ) chunk = self.__chunk_iter.next() chunk_data = chunk["data"][self.__position % chunk_size :] if not chunk_data: raise CorruptGridFile("truncated chunk") self.__position += len(chunk_data) self.__buffer = EMPTY return chunk_data def read(self, size: int = -1) -> bytes: """Read at most `size` bytes from the file (less if there isn't enough data). The bytes are returned as an instance of :class:`str` (:class:`bytes` in python 3). If `size` is negative or omitted all data is read. :Parameters: - `size` (optional): the number of bytes to read .. versionchanged:: 3.8 This method now only checks for extra chunks after reading the entire file. Previously, this method would check for extra chunks on every call. """ self._ensure_file() remainder = int(self.length) - self.__position if size < 0 or size > remainder: size = remainder if size == 0: return EMPTY received = 0 data = io.BytesIO() while received < size: chunk_data = self.readchunk() received += len(chunk_data) data.write(chunk_data) # Detect extra chunks after reading the entire file. if size == remainder and self.__chunk_iter: try: self.__chunk_iter.next() except StopIteration: pass self.__position -= received - size # Return 'size' bytes and store the rest. data.seek(size) self.__buffer = data.read() data.seek(0) return data.read(size) def readline(self, size: int = -1) -> bytes: # type: ignore[override] """Read one line or up to `size` bytes from the file. :Parameters: - `size` (optional): the maximum number of bytes to read """ remainder = int(self.length) - self.__position if size < 0 or size > remainder: size = remainder if size == 0: return EMPTY received = 0 data = io.BytesIO() while received < size: chunk_data = self.readchunk() pos = chunk_data.find(NEWLN, 0, size) if pos != -1: size = received + pos + 1 received += len(chunk_data) data.write(chunk_data) if pos != -1: break self.__position -= received - size # Return 'size' bytes and store the rest. data.seek(size) self.__buffer = data.read() data.seek(0) return data.read(size) def tell(self) -> int: """Return the current position of this file.""" return self.__position def seek(self, pos: int, whence: int = _SEEK_SET) -> int: """Set the current position of this file. :Parameters: - `pos`: the position (or offset if using relative positioning) to seek to - `whence` (optional): where to seek from. :attr:`os.SEEK_SET` (``0``) for absolute file positioning, :attr:`os.SEEK_CUR` (``1``) to seek relative to the current position, :attr:`os.SEEK_END` (``2``) to seek relative to the file's end. .. versionchanged:: 4.1 The method now returns the new position in the file, to conform to the behavior of :meth:`io.IOBase.seek`. """ if whence == _SEEK_SET: new_pos = pos elif whence == _SEEK_CUR: new_pos = self.__position + pos elif whence == _SEEK_END: new_pos = int(self.length) + pos else: raise IOError(22, "Invalid value for `whence`") if new_pos < 0: raise IOError(22, "Invalid value for `pos` - must be positive") # Optimization, continue using the same buffer and chunk iterator. if new_pos == self.__position: return new_pos self.__position = new_pos self.__buffer = EMPTY if self.__chunk_iter: self.__chunk_iter.close() self.__chunk_iter = None return new_pos def seekable(self) -> bool: return True def __iter__(self) -> "GridOut": """Return an iterator over all of this file's data. The iterator will return lines (delimited by ``b'\\n'``) of :class:`bytes`. This can be useful when serving files using a webserver that handles such an iterator efficiently. .. versionchanged:: 3.8 The iterator now raises :class:`CorruptGridFile` when encountering any truncated, missing, or extra chunk in a file. The previous behavior was to only raise :class:`CorruptGridFile` on a missing chunk. .. versionchanged:: 4.0 The iterator now iterates over *lines* in the file, instead of chunks, to conform to the base class :py:class:`io.IOBase`. Use :meth:`GridOut.readchunk` to read chunk by chunk instead of line by line. """ return self def close(self) -> None: """Make GridOut more generically file-like.""" if self.__chunk_iter: self.__chunk_iter.close() self.__chunk_iter = None super().close() def write(self, value: Any) -> NoReturn: raise io.UnsupportedOperation("write") def writelines(self, lines: Any) -> NoReturn: raise io.UnsupportedOperation("writelines") def writable(self) -> bool: return False def __enter__(self) -> "GridOut": """Makes it possible to use :class:`GridOut` files with the context manager protocol. """ return self def __exit__(self, exc_type: Any, exc_val: Any, exc_tb: Any) -> Any: """Makes it possible to use :class:`GridOut` files with the context manager protocol. """ self.close() return False def fileno(self) -> NoReturn: raise io.UnsupportedOperation("fileno") def flush(self) -> None: # GridOut is read-only, so flush does nothing. pass def isatty(self) -> bool: return False def truncate(self, size: Optional[int] = None) -> NoReturn: # See https://docs.python.org/3/library/io.html#io.IOBase.writable # for why truncate has to raise. raise io.UnsupportedOperation("truncate") # Override IOBase.__del__ otherwise it will lead to __getattr__ on # __IOBase_closed which calls _ensure_file and potentially performs I/O. # We cannot do I/O in __del__ since it can lead to a deadlock. def __del__(self) -> None: pass class _GridOutChunkIterator(object): """Iterates over a file's chunks using a single cursor. Raises CorruptGridFile when encountering any truncated, missing, or extra chunk in a file. """ def __init__( self, grid_out: GridOut, chunks: Collection, session: Optional[ClientSession], next_chunk: Any, ) -> None: self._id = grid_out._id self._chunk_size = int(grid_out.chunk_size) self._length = int(grid_out.length) self._chunks = chunks self._session = session self._next_chunk = next_chunk self._num_chunks = math.ceil(float(self._length) / self._chunk_size) self._cursor = None _cursor: Optional[Cursor] def expected_chunk_length(self, chunk_n: int) -> int: if chunk_n < self._num_chunks - 1: return self._chunk_size return self._length - (self._chunk_size * (self._num_chunks - 1)) def __iter__(self) -> "_GridOutChunkIterator": return self def _create_cursor(self) -> None: filter = {"files_id": self._id} if self._next_chunk > 0: filter["n"] = {"$gte": self._next_chunk} _disallow_transactions(self._session) self._cursor = self._chunks.find(filter, sort=[("n", 1)], session=self._session) def _next_with_retry(self) -> Mapping[str, Any]: """Return the next chunk and retry once on CursorNotFound. We retry on CursorNotFound to maintain backwards compatibility in cases where two calls to read occur more than 10 minutes apart (the server's default cursor timeout). """ if self._cursor is None: self._create_cursor() assert self._cursor is not None try: return self._cursor.next() except CursorNotFound: self._cursor.close() self._create_cursor() return self._cursor.next() def next(self) -> Mapping[str, Any]: try: chunk = self._next_with_retry() except StopIteration: if self._next_chunk >= self._num_chunks: raise raise CorruptGridFile("no chunk #%d" % self._next_chunk) if chunk["n"] != self._next_chunk: self.close() raise CorruptGridFile( "Missing chunk: expected chunk #%d but found " "chunk with n=%d" % (self._next_chunk, chunk["n"]) ) if chunk["n"] >= self._num_chunks: # According to spec, ignore extra chunks if they are empty. if len(chunk["data"]): self.close() raise CorruptGridFile( "Extra chunk found: expected %d chunks but found " "chunk with n=%d" % (self._num_chunks, chunk["n"]) ) expected_length = self.expected_chunk_length(chunk["n"]) if len(chunk["data"]) != expected_length: self.close() raise CorruptGridFile( "truncated chunk #%d: expected chunk length to be %d but " "found chunk with length %d" % (chunk["n"], expected_length, len(chunk["data"])) ) self._next_chunk += 1 return chunk __next__ = next def close(self) -> None: if self._cursor: self._cursor.close() self._cursor = None class GridOutIterator(object): def __init__(self, grid_out: GridOut, chunks: Collection, session: ClientSession): self.__chunk_iter = _GridOutChunkIterator(grid_out, chunks, session, 0) def __iter__(self) -> "GridOutIterator": return self def next(self) -> bytes: chunk = self.__chunk_iter.next() return bytes(chunk["data"]) __next__ = next class GridOutCursor(Cursor): """A cursor / iterator for returning GridOut objects as the result of an arbitrary query against the GridFS files collection. """ def __init__( self, collection: Collection, filter: Optional[Mapping[str, Any]] = None, skip: int = 0, limit: int = 0, no_cursor_timeout: bool = False, sort: Optional[Any] = None, batch_size: int = 0, session: Optional[ClientSession] = None, ) -> None: """Create a new cursor, similar to the normal :class:`~pymongo.cursor.Cursor`. Should not be called directly by application developers - see the :class:`~gridfs.GridFS` method :meth:`~gridfs.GridFS.find` instead. .. versionadded 2.7 .. seealso:: The MongoDB documentation on `cursors `_. """ _disallow_transactions(session) collection = _clear_entity_type_registry(collection) # Hold on to the base "fs" collection to create GridOut objects later. self.__root_collection = collection super(GridOutCursor, self).__init__( collection.files, filter, skip=skip, limit=limit, no_cursor_timeout=no_cursor_timeout, sort=sort, batch_size=batch_size, session=session, ) def next(self) -> GridOut: """Get next GridOut object from cursor.""" _disallow_transactions(self.session) next_file = super(GridOutCursor, self).next() return GridOut(self.__root_collection, file_document=next_file, session=self.session) __next__ = next def add_option(self, *args: Any, **kwargs: Any) -> NoReturn: raise NotImplementedError("Method does not exist for GridOutCursor") def remove_option(self, *args: Any, **kwargs: Any) -> NoReturn: raise NotImplementedError("Method does not exist for GridOutCursor") def _clone_base(self, session: ClientSession) -> "GridOutCursor": """Creates an empty GridOutCursor for information to be copied into.""" return GridOutCursor(self.__root_collection, session=session)