# 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."""
from __future__ import annotations
import datetime
import io
import math
import os
import warnings
from typing import Any, Iterable, Mapping, NoReturn, Optional
from bson.int64 import Int64
from bson.objectid import ObjectId
from gridfs.errors import CorruptGridFile, FileExists, NoFile
from pymongo import ASCENDING
from pymongo.client_session import ClientSession
from pymongo.collection import Collection
from pymongo.common import MAX_MESSAGE_SIZE
from pymongo.cursor import Cursor
from pymongo.errors import (
BulkWriteError,
ConfigurationError,
CursorNotFound,
DuplicateKeyError,
InvalidOperation,
OperationFailure,
)
from pymongo.helpers import _check_write_command_response
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
# The number of chunked bytes to buffer before calling insert_many.
_UPLOAD_BUFFER_SIZE = MAX_MESSAGE_SIZE
# The number of chunk documents to buffer before calling insert_many.
_UPLOAD_BUFFER_CHUNKS = 100000
# Rough BSON overhead of a chunk document not including the chunk data itself.
# Essentially len(encode({"_id": ObjectId(), "files_id": ObjectId(), "n": 1, "data": ""}))
_CHUNK_OVERHEAD = 60
_C_INDEX: dict[str, Any] = {"files_id": ASCENDING, "n": ASCENDING}
_F_INDEX: dict[str, Any] = {"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."""
warn_str = ""
if docstring.startswith("DEPRECATED,"):
warn_str = (
f"GridIn property '{field_name}' is deprecated and will be removed in PyMongo 5.0"
)
def getter(self: Any) -> Any:
if warn_str:
warnings.warn(warn_str, stacklevel=2, category=DeprecationWarning)
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 warn_str:
warnings.warn(warn_str, stacklevel=2, category=DeprecationWarning)
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 = "{}\n\n{}".format(
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."""
warn_str = ""
if docstring.startswith("DEPRECATED,"):
warn_str = (
f"GridOut property '{field_name}' is deprecated and will be removed in PyMongo 5.0"
)
def getter(self: Any) -> Any:
if warn_str:
warnings.warn(warn_str, stacklevel=2, category=DeprecationWarning)
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:
"""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
<http://dochub.mongodb.org/core/gridfsspec>`_ 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`.
:param root_collection: root collection to write to
:param session: a
:class:`~pymongo.client_session.ClientSession` to use for all
commands
:param kwargs: Any: 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)
object.__setattr__(self, "_buffered_docs", [])
object.__setattr__(self, "_buffered_docs_size", 0)
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", "DEPRECATED, will be removed in PyMongo 5.0. 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",
"DEPRECATED, will be removed in PyMongo 5.0. MD5 of the contents of this file if an md5 sum was created.",
closed_only=True,
)
_buffer: io.BytesIO
_closed: bool
_buffered_docs: list[dict[str, Any]]
_buffered_docs_size: int
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, force: bool = False) -> None:
"""Flush `data` to a chunk."""
self.__ensure_indexes()
assert len(data) <= self.chunk_size
if data:
self._buffered_docs.append(
{"files_id": self._file["_id"], "n": self._chunk_number, "data": data}
)
self._buffered_docs_size += len(data) + _CHUNK_OVERHEAD
if not self._buffered_docs:
return
# Limit to 100,000 chunks or 32MB (+1 chunk) of data.
if (
force
or self._buffered_docs_size >= _UPLOAD_BUFFER_SIZE
or len(self._buffered_docs) >= _UPLOAD_BUFFER_CHUNKS
):
try:
self._chunks.insert_many(self._buffered_docs, session=self._session)
except BulkWriteError as exc:
# For backwards compatibility, raise an insert_one style exception.
write_errors = exc.details["writeErrors"]
for err in write_errors:
if err.get("code") in (11000, 11001, 12582): # Duplicate key errors
self._raise_file_exists(self._file["_id"])
result = {"writeErrors": write_errors}
wces = exc.details["writeConcernErrors"]
if wces:
result["writeConcernError"] = wces[-1]
_check_write_command_response(result)
raise
self._buffered_docs = []
self._buffered_docs_size = 0
self._chunk_number += 1
self._position += len(data)
def __flush_buffer(self, force: bool = False) -> None:
"""Flush the buffer contents out to a chunk."""
self.__flush_data(self._buffer.getvalue(), force=force)
self._buffer.close()
self._buffer = io.BytesIO()
def __flush(self) -> Any:
"""Flush the file to the database."""
try:
self.__flush_buffer(force=True)
# The GridFS spec says length SHOULD be an Int64.
self._file["length"] = Int64(self._position)
self._file["uploadDate"] = datetime.datetime.now(tz=datetime.timezone.utc)
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.
:param 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") from None
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"
) from None
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 separators.
"""
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`.
:param root_collection: root collection to read from
:param file_id: value of ``"_id"`` for the file to read
:param file_document: file document from
`root_collection.files`
:param session: 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
# Start position within the current buffered chunk.
self.__buffer_pos = 0
self.__chunk_iter = None
# Position within the total file.
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", "DEPRECATED, will be removed in PyMongo 5.0. 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", "DEPRECATED, will be removed in PyMongo 5.0. 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",
"DEPRECATED, will be removed in PyMongo 5.0. 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(
f"no file in gridfs collection {self.__files!r} with _id {self.__file_id!r}"
)
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) - self.__buffer_pos
chunk_data = EMPTY
chunk_size = int(self.chunk_size)
if received > 0:
chunk_data = self.__buffer[self.__buffer_pos :]
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
self.__buffer_pos = 0
return chunk_data
def _read_size_or_line(self, size: int = -1, line: bool = False) -> bytes:
"""Internal read() and readline() helper."""
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 = []
while received < size:
needed = size - received
if self.__buffer:
# Optimization: Read the buffer with zero byte copies.
buf = self.__buffer
chunk_start = self.__buffer_pos
chunk_data = memoryview(buf)[self.__buffer_pos :]
self.__buffer = EMPTY
self.__buffer_pos = 0
self.__position += len(chunk_data)
else:
buf = self.readchunk()
chunk_start = 0
chunk_data = memoryview(buf)
if line:
pos = buf.find(NEWLN, chunk_start, chunk_start + needed) - chunk_start
if pos >= 0:
# Decrease size to exit the loop.
size = received + pos + 1
needed = pos + 1
if len(chunk_data) > needed:
data.append(chunk_data[:needed])
# Optimization: Save the buffer with zero byte copies.
self.__buffer = buf
self.__buffer_pos = chunk_start + needed
self.__position -= len(self.__buffer) - self.__buffer_pos
else:
data.append(chunk_data)
received += len(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
return b"".join(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:`bytes`
If `size` is negative or omitted all data is read.
:param size: 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.
"""
return self._read_size_or_line(size=size)
def readline(self, size: int = -1) -> bytes: # type: ignore[override]
"""Read one line or up to `size` bytes from the file.
:param size: the maximum number of bytes to read
"""
return self._read_size_or_line(size=size, line=True)
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.
:param pos: the position (or offset if using relative
positioning) to seek to
:param whence: 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 OSError(22, "Invalid value for `whence`")
if new_pos < 0:
raise OSError(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
self.__buffer_pos = 0
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:
"""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) from None
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:
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 <https://dochub.mongodb.org/core/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().__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().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: Optional[ClientSession]) -> GridOutCursor:
"""Creates an empty GridOutCursor for information to be copied into."""
return GridOutCursor(self.__root_collection, session=session)