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# Copyright 2009-2012 10gen, 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 math
import os
import sys
if sys.version_info[0] == 3:
from io import BytesIO as StringIO
else:
# 2to3 will turn cStringIO into io. That's okay
# since we'll never get here under python3.
from cStringIO import StringIO
from bson.binary import Binary
from bson.objectid import ObjectId
from bson.py3compat import b, binary_type, string_types, text_type
from gridfs.errors import (CorruptGridFile,
FileExists,
NoFile,
UnsupportedAPI)
from pymongo import ASCENDING
from pymongo.collection import Collection
from pymongo.errors import DuplicateKeyError
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."""
DEFAULT_CHUNK_SIZE = 256 * 1024
def _create_property(field_name, docstring,
read_only=False, closed_only=False):
"""Helper for creating properties to read/write to files.
"""
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({"_id": self._file["_id"]},
{"$set": {field_name: value}}, safe=True)
self._file[field_name] = value
if read_only:
docstring = 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)
class GridIn(object):
"""Class to write data to GridFS.
"""
def __init__(self, root_collection, **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: 256 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
- `**kwargs` (optional): file level options (see above)
"""
if not isinstance(root_collection, Collection):
raise TypeError("root_collection must be an "
"instance of Collection")
# 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")
# Defaults
kwargs["_id"] = kwargs.get("_id", ObjectId())
kwargs["chunkSize"] = kwargs.get("chunkSize", DEFAULT_CHUNK_SIZE)
root_collection.chunks.ensure_index([("files_id", ASCENDING),
("n", ASCENDING)],
unique=True)
object.__setattr__(self, "_coll", root_collection)
object.__setattr__(self, "_chunks", root_collection.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)
@property
def closed(self):
"""Is this file closed?
"""
return self._closed
_id = _create_property("_id", "The ``'_id'`` value for this file.",
read_only=True)
filename = _create_property("filename", "Name of this file.")
content_type = _create_property("contentType", "Mime-type for this file.")
length = _create_property("length", "Length (in bytes) of this file.",
closed_only=True)
chunk_size = _create_property("chunkSize", "Chunk size for this file.",
read_only=True)
upload_date = _create_property("uploadDate",
"Date that this file was uploaded.",
closed_only=True)
md5 = _create_property("md5", "MD5 of the contents of this file "
"(generated on the server).",
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):
object.__setattr__(self, name, value)
if self._closed:
self._coll.files.update({"_id": self._file["_id"]},
{"$set": {name: value}}, safe=True)
def __flush_data(self, data):
"""Flush `data` to a chunk.
"""
if not data:
return
assert(len(data) <= self.chunk_size)
chunk = {"files_id": self._file["_id"],
"n": self._chunk_number,
"data": Binary(data)}
self._chunks.insert(chunk)
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.
"""
self.__flush_buffer()
md5 = self._coll.database.command("filemd5", self._id,
root=self._coll.name)["md5"]
self._file["md5"] = md5
self._file["length"] = self._position
self._file["uploadDate"] = datetime.datetime.utcnow()
try:
return self._coll.files.insert(self._file, safe=True)
except DuplicateKeyError:
raise FileExists("file with _id %r already exists" % self._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 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
.. versionadded:: 1.9
The ability to write :class:`unicode`, if the file has an
:attr:`encoding` attribute.
"""
if self._closed:
raise ValueError("cannot write to a closed file")
try:
# file-like
read = data.read
except AttributeError:
# string
if not isinstance(data, string_types):
raise TypeError("can only write strings or file-like objects")
if isinstance(data, unicode):
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:
to_write = read(space)
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 __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 propogate.
"""
self.close()
# propogate exceptions
return False
class GridOut(object):
"""Class to read data out of GridFS.
"""
def __init__(self, root_collection, file_id=None, file_document=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`: value of ``"_id"`` for the file to read
- `file_document`: file document from `root_collection.files`
.. versionadded:: 1.9
The `file_document` parameter.
"""
if not isinstance(root_collection, Collection):
raise TypeError("root_collection must be an "
"instance of Collection")
self.__chunks = root_collection.chunks
files = root_collection.files
self._file = file_document or files.find_one({"_id": file_id})
if not self._file:
raise NoFile("no file in gridfs collection %r with _id %r" %
(files, file_id))
self.__buffer = EMPTY
self.__position = 0
_id = _create_property("_id", "The ``'_id'`` value for this file.", True)
name = _create_property("filename", "Name of this file.", True)
content_type = _create_property("contentType", "Mime-type for this file.",
True)
length = _create_property("length", "Length (in bytes) of this file.",
True)
chunk_size = _create_property("chunkSize", "Chunk size for this file.",
True)
upload_date = _create_property("uploadDate",
"Date that this file was first uploaded.",
True)
aliases = _create_property("aliases", "List of aliases for this file.",
True)
metadata = _create_property("metadata", "Metadata attached to this file.",
True)
md5 = _create_property("md5", "MD5 of the contents of this file "
"(generated on the server).", True)
def __getattr__(self, name):
if name in self._file:
return self._file[name]
raise AttributeError("GridOut object has no attribute '%s'" % name)
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
"""
if size == 0:
return ""
remainder = int(self.length) - self.__position
if size < 0 or size > remainder:
size = remainder
received = len(self.__buffer)
chunk_number = int((received + self.__position) / self.chunk_size)
chunks = []
while received < size:
chunk = self.__chunks.find_one({"files_id": self._id,
"n": chunk_number})
if not chunk:
raise CorruptGridFile("no chunk #%d" % chunk_number)
if received:
chunk_data = chunk["data"]
else:
chunk_data = chunk["data"][self.__position % self.chunk_size:]
received += len(chunk_data)
chunks.append(chunk_data)
chunk_number += 1
data = EMPTY.join([self.__buffer] + chunks)
self.__position += size
to_return = data[:size]
self.__buffer = data[size:]
return to_return
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
.. versionadded:: 1.9
"""
bytes = EMPTY
while len(bytes) != size:
byte = self.read(1)
bytes += byte
if byte == EMPTY or byte == NEWLN:
break
return bytes
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")
self.__position = new_pos
self.__buffer = EMPTY
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.
"""
return GridOutIterator(self, self.__chunks)
def close(self):
"""Make GridOut more generically file-like."""
pass
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.
"""
return False
class GridOutIterator(object):
def __init__(self, grid_out, chunks):
self.__id = grid_out._id
self.__chunks = chunks
self.__current_chunk = 0
self.__max_chunk = math.ceil(float(grid_out.length) /
grid_out.chunk_size)
def __iter__(self):
return self
def next(self):
if self.__current_chunk >= self.__max_chunk:
raise StopIteration
chunk = self.__chunks.find_one({"files_id": self.__id,
"n": self.__current_chunk})
if not chunk:
raise CorruptGridFile("no chunk #%d" % self.__current_chunk)
self.__current_chunk += 1
return binary_type(chunk["data"])
class GridFile(object):
"""No longer supported.
.. versionchanged:: 1.6
The GridFile class is no longer supported.
"""
def __init__(self, *args, **kwargs):
raise UnsupportedAPI("The GridFile class is no longer supported. "
"Please use GridIn or GridOut instead.")
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