# 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 hashlib
import io
import math
import os
from bson.son import SON
from bson.binary import Binary
from bson.objectid import ObjectId
from bson.py3compat import text_type, StringIO
from gridfs.errors import CorruptGridFile, FileExists, NoFile
from pymongo import ASCENDING
from pymongo.collection import Collection
from pymongo.cursor import Cursor
from pymongo.errors import (ConfigurationError,
CursorNotFound,
DuplicateKeyError,
OperationFailure)
from pymongo.read_preferences import ReadPreference
try:
_SEEK_SET = os.SEEK_SET
_SEEK_CUR = os.SEEK_CUR
_SEEK_END = os.SEEK_END
# before 2.5
except AttributeError:
_SEEK_SET = 0
_SEEK_CUR = 1
_SEEK_END = 2
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([("files_id", ASCENDING), ("n", ASCENDING)])
_F_INDEX = SON([("filename", ASCENDING), ("uploadDate", ASCENDING)])
def _grid_in_property(field_name, docstring, read_only=False,
closed_only=False):
"""Create a GridIn property."""
def getter(self):
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, value):
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, docstring):
"""Create a GridOut property."""
def getter(self):
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, **kwargs):
"""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)
class GridIn(object):
"""Class to write data to GridFS.
"""
def __init__(
self, root_collection, session=None, disable_md5=False, **kwargs):
"""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. In Python 2,
any :class:`unicode` that is written to the file will be
converted to a :class:`str`. In Python 3, 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
- `disable_md5` (optional): When True, an MD5 checksum will not be
computed for the uploaded file. Useful in environments where
MD5 cannot be used for regulatory or other reasons. Defaults to
False.
- `**kwargs` (optional): file level options (see above)
.. 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')
# 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)
if not disable_md5:
kwargs["md5"] = hashlib.md5()
# 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", StringIO())
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, index_key, unique):
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):
if not object.__getattribute__(self, "_ensured_index"):
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):
"""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):
"""Is this file closed?
"""
return self._closed
_id = _grid_in_property("_id", "The ``'_id'`` value for this file.",
read_only=True)
filename = _grid_in_property("filename", "Name of this file.")
name = _grid_in_property("filename", "Alias for `filename`.")
content_type = _grid_in_property("contentType", "Mime-type for this file.")
length = _grid_in_property("length", "Length (in bytes) of this file.",
closed_only=True)
chunk_size = _grid_in_property("chunkSize", "Chunk size for this file.",
read_only=True)
upload_date = _grid_in_property("uploadDate",
"Date that this file was uploaded.",
closed_only=True)
md5 = _grid_in_property("md5", "MD5 of the contents of this file "
"if an md5 sum was created.",
closed_only=True)
def __getattr__(self, name):
if name in self._file:
return self._file[name]
raise AttributeError("GridIn object has no attribute '%s'" % name)
def __setattr__(self, name, value):
# 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):
"""Flush `data` to a chunk.
"""
self.__ensure_indexes()
if 'md5' in self._file:
self._file['md5'].update(data)
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):
"""Flush the buffer contents out to a chunk.
"""
self.__flush_data(self._buffer.getvalue())
self._buffer.close()
self._buffer = StringIO()
def __flush(self):
"""Flush the file to the database.
"""
try:
self.__flush_buffer()
if "md5" in self._file:
self._file["md5"] = self._file["md5"].hexdigest()
self._file["length"] = 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):
"""Raise a FileExists exception for the given file_id."""
raise FileExists("file with _id %r already exists" % file_id)
def close(self):
"""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=-1):
raise io.UnsupportedOperation('read')
def readable(self):
return False
def seekable(self):
return False
def write(self, data):
"""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:`unicode` (:class:`str` in python 3) 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:`str` (:class:`bytes` in python 3), a file-like object,
or an instance of :class:`unicode` (:class:`str` in python 3).
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, (text_type, bytes)):
raise TypeError("can only write strings or file-like objects")
if isinstance(data, text_type):
try:
data = data.encode(self.encoding)
except AttributeError:
raise TypeError("must specify an encoding for file in "
"order to write %s" % (text_type.__name__,))
read = StringIO(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:
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):
"""Write a sequence of strings to the file.
Does not add seperators.
"""
for line in sequence:
self.write(line)
def writeable(self):
return True
def __enter__(self):
"""Support for the context manager protocol.
"""
return self
def __exit__(self, exc_type, exc_val, exc_tb):
"""Support for the context manager protocol.
Close the file and allow exceptions to propagate.
"""
self.close()
# propagate exceptions
return False
class GridOut(object):
"""Class to read data out of GridFS.
"""
def __init__(self, root_collection, file_id=None, file_document=None,
session=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")
root_collection = _clear_entity_type_registry(root_collection)
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 = _grid_out_property("_id", "The ``'_id'`` value for this file.")
filename = _grid_out_property("filename", "Name of this file.")
name = _grid_out_property("filename", "Alias for `filename`.")
content_type = _grid_out_property("contentType", "Mime-type for this file.")
length = _grid_out_property("length", "Length (in bytes) of this file.")
chunk_size = _grid_out_property("chunkSize", "Chunk size for this file.")
upload_date = _grid_out_property("uploadDate",
"Date that this file was first uploaded.")
aliases = _grid_out_property("aliases", "List of aliases for this file.")
metadata = _grid_out_property("metadata", "Metadata attached to this file.")
md5 = _grid_out_property("md5", "MD5 of the contents of this file "
"if an md5 sum was created.")
def _ensure_file(self):
if not self._file:
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):
self._ensure_file()
if name in self._file:
return self._file[name]
raise AttributeError("GridOut object has no attribute '%s'" % name)
def readable(self):
return True
def readchunk(self):
"""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=-1):
"""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 = StringIO()
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=-1):
"""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 = StringIO()
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):
"""Return the current position of this file.
"""
return self.__position
def seek(self, pos, whence=_SEEK_SET):
"""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.
"""
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
self.__position = new_pos
self.__buffer = EMPTY
if self.__chunk_iter:
self.__chunk_iter.close()
self.__chunk_iter = None
def seekable(self):
return True
def __iter__(self):
"""Return an iterator over all of this file's data.
The iterator will return chunk-sized instances of
:class:`str` (:class:`bytes` in python 3). This can be
useful when serving files using a webserver that handles
such an iterator efficiently.
.. note::
This is different from :py:class:`io.IOBase` which iterates over
*lines* in the file. Use :meth:`GridOut.readline` to read line by
line instead of chunk by chunk.
.. 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.
"""
return GridOutIterator(self, self.__chunks, self._session)
def close(self):
"""Make GridOut more generically file-like."""
if self.__chunk_iter:
self.__chunk_iter.close()
self.__chunk_iter = None
def write(self, value):
raise io.UnsupportedOperation('write')
def __enter__(self):
"""Makes it possible to use :class:`GridOut` files
with the context manager protocol.
"""
return self
def __exit__(self, exc_type, exc_val, exc_tb):
"""Makes it possible to use :class:`GridOut` files
with the context manager protocol.
"""
self.close()
return False
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, chunks, session, next_chunk):
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
def expected_chunk_length(self, chunk_n):
if chunk_n < self._num_chunks - 1:
return self._chunk_size
return self._length - (self._chunk_size * (self._num_chunks - 1))
def __iter__(self):
return self
def _create_cursor(self):
filter = {"files_id": self._id}
if self._next_chunk > 0:
filter["n"] = {"$gte": self._next_chunk}
self._cursor = self._chunks.find(filter, sort=[("n", 1)],
session=self._session)
def _next_with_retry(self):
"""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()
try:
return self._cursor.next()
except CursorNotFound:
self._cursor.close()
self._create_cursor()
return self._cursor.next()
def next(self):
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):
if self._cursor:
self._cursor.close()
self._cursor = None
class GridOutIterator(object):
def __init__(self, grid_out, chunks, session):
self.__chunk_iter = _GridOutChunkIterator(grid_out, chunks, session, 0)
def __iter__(self):
return self
def next(self):
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, filter=None, skip=0, limit=0,
no_cursor_timeout=False, sort=None, batch_size=0,
session=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
.. mongodoc:: cursors
"""
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):
"""Get next GridOut object from cursor.
"""
# Work around "super is not iterable" issue in Python 3.x
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, **kwargs):
raise NotImplementedError("Method does not exist for GridOutCursor")
def remove_option(self, *args, **kwargs):
raise NotImplementedError("Method does not exist for GridOutCursor")
def _clone_base(self, session):
"""Creates an empty GridOutCursor for information to be copied into.
"""
return GridOutCursor(self.__root_collection, session=session)