283 lines
9.0 KiB
Python
283 lines
9.0 KiB
Python
# Copyright 2009-2015 MongoDB, Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""Tools for working with MongoDB ObjectIds."""
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import binascii
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import calendar
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import datetime
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import os
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import struct
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import threading
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import time
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from random import SystemRandom
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from typing import Any, NoReturn, Optional, Type, Union
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from bson.errors import InvalidId
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from bson.tz_util import utc
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_MAX_COUNTER_VALUE = 0xFFFFFF
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def _raise_invalid_id(oid: str) -> NoReturn:
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raise InvalidId(
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"%r is not a valid ObjectId, it must be a 12-byte input"
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" or a 24-character hex string" % oid
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)
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def _random_bytes() -> bytes:
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"""Get the 5-byte random field of an ObjectId."""
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return os.urandom(5)
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class ObjectId:
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"""A MongoDB ObjectId."""
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_pid = os.getpid()
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_inc = SystemRandom().randint(0, _MAX_COUNTER_VALUE)
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_inc_lock = threading.Lock()
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__random = _random_bytes()
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__slots__ = ("__id",)
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_type_marker = 7
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def __init__(self, oid: Optional[Union[str, "ObjectId", bytes]] = None) -> None:
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"""Initialize a new ObjectId.
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An ObjectId is a 12-byte unique identifier consisting of:
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- a 4-byte value representing the seconds since the Unix epoch,
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- a 5-byte random value,
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- a 3-byte counter, starting with a random value.
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By default, ``ObjectId()`` creates a new unique identifier. The
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optional parameter `oid` can be an :class:`ObjectId`, or any 12
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:class:`bytes`.
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For example, the 12 bytes b'foo-bar-quux' do not follow the ObjectId
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specification but they are acceptable input::
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>>> ObjectId(b'foo-bar-quux')
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ObjectId('666f6f2d6261722d71757578')
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`oid` can also be a :class:`str` of 24 hex digits::
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>>> ObjectId('0123456789ab0123456789ab')
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ObjectId('0123456789ab0123456789ab')
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Raises :class:`~bson.errors.InvalidId` if `oid` is not 12 bytes nor
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24 hex digits, or :class:`TypeError` if `oid` is not an accepted type.
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:Parameters:
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- `oid` (optional): a valid ObjectId.
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.. seealso:: The MongoDB documentation on `ObjectIds <http://dochub.mongodb.org/core/objectids>`_.
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.. versionchanged:: 3.8
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:class:`~bson.objectid.ObjectId` now implements the `ObjectID
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specification version 0.2
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<https://github.com/mongodb/specifications/blob/master/source/
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objectid.rst>`_.
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"""
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if oid is None:
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self.__generate()
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elif isinstance(oid, bytes) and len(oid) == 12:
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self.__id = oid
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else:
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self.__validate(oid)
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@classmethod
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def from_datetime(cls: Type["ObjectId"], generation_time: datetime.datetime) -> "ObjectId":
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"""Create a dummy ObjectId instance with a specific generation time.
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This method is useful for doing range queries on a field
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containing :class:`ObjectId` instances.
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.. warning::
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It is not safe to insert a document containing an ObjectId
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generated using this method. This method deliberately
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eliminates the uniqueness guarantee that ObjectIds
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generally provide. ObjectIds generated with this method
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should be used exclusively in queries.
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`generation_time` will be converted to UTC. Naive datetime
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instances will be treated as though they already contain UTC.
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An example using this helper to get documents where ``"_id"``
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was generated before January 1, 2010 would be:
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>>> gen_time = datetime.datetime(2010, 1, 1)
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>>> dummy_id = ObjectId.from_datetime(gen_time)
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>>> result = collection.find({"_id": {"$lt": dummy_id}})
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:Parameters:
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- `generation_time`: :class:`~datetime.datetime` to be used
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as the generation time for the resulting ObjectId.
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"""
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offset = generation_time.utcoffset()
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if offset is not None:
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generation_time = generation_time - offset
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timestamp = calendar.timegm(generation_time.timetuple())
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oid = struct.pack(">I", int(timestamp)) + b"\x00\x00\x00\x00\x00\x00\x00\x00"
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return cls(oid)
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@classmethod
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def is_valid(cls: Type["ObjectId"], oid: Any) -> bool:
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"""Checks if a `oid` string is valid or not.
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:Parameters:
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- `oid`: the object id to validate
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.. versionadded:: 2.3
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"""
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if not oid:
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return False
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try:
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ObjectId(oid)
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return True
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except (InvalidId, TypeError):
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return False
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@classmethod
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def _random(cls) -> bytes:
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"""Generate a 5-byte random number once per process."""
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pid = os.getpid()
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if pid != cls._pid:
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cls._pid = pid
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cls.__random = _random_bytes()
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return cls.__random
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def __generate(self) -> None:
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"""Generate a new value for this ObjectId."""
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# 4 bytes current time
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oid = struct.pack(">I", int(time.time()))
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# 5 bytes random
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oid += ObjectId._random()
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# 3 bytes inc
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with ObjectId._inc_lock:
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oid += struct.pack(">I", ObjectId._inc)[1:4]
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ObjectId._inc = (ObjectId._inc + 1) % (_MAX_COUNTER_VALUE + 1)
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self.__id = oid
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def __validate(self, oid: Any) -> None:
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"""Validate and use the given id for this ObjectId.
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Raises TypeError if id is not an instance of
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(:class:`basestring` (:class:`str` or :class:`bytes`
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in python 3), ObjectId) and InvalidId if it is not a
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valid ObjectId.
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:Parameters:
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- `oid`: a valid ObjectId
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"""
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if isinstance(oid, ObjectId):
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self.__id = oid.binary
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elif isinstance(oid, str):
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if len(oid) == 24:
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try:
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self.__id = bytes.fromhex(oid)
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except (TypeError, ValueError):
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_raise_invalid_id(oid)
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else:
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_raise_invalid_id(oid)
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else:
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raise TypeError(f"id must be an instance of (bytes, str, ObjectId), not {type(oid)}")
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@property
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def binary(self) -> bytes:
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"""12-byte binary representation of this ObjectId."""
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return self.__id
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@property
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def generation_time(self) -> datetime.datetime:
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"""A :class:`datetime.datetime` instance representing the time of
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generation for this :class:`ObjectId`.
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The :class:`datetime.datetime` is timezone aware, and
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represents the generation time in UTC. It is precise to the
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second.
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"""
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timestamp = struct.unpack(">I", self.__id[0:4])[0]
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return datetime.datetime.fromtimestamp(timestamp, utc)
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def __getstate__(self) -> bytes:
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"""Return value of object for pickling.
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needed explicitly because __slots__() defined.
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"""
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return self.__id
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def __setstate__(self, value: Any) -> None:
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"""Explicit state set from pickling"""
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# Provide backwards compatibility with OIDs
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# pickled with pymongo-1.9 or older.
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if isinstance(value, dict):
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oid = value["_ObjectId__id"]
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else:
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oid = value
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# ObjectIds pickled in python 2.x used `str` for __id.
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# In python 3.x this has to be converted to `bytes`
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# by encoding latin-1.
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if isinstance(oid, str):
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self.__id = oid.encode("latin-1")
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else:
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self.__id = oid
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def __str__(self) -> str:
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return binascii.hexlify(self.__id).decode()
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def __repr__(self):
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return f"ObjectId('{str(self)}')"
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def __eq__(self, other: Any) -> bool:
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if isinstance(other, ObjectId):
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return self.__id == other.binary
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return NotImplemented
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def __ne__(self, other: Any) -> bool:
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if isinstance(other, ObjectId):
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return self.__id != other.binary
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return NotImplemented
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def __lt__(self, other: Any) -> bool:
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if isinstance(other, ObjectId):
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return self.__id < other.binary
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return NotImplemented
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def __le__(self, other: Any) -> bool:
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if isinstance(other, ObjectId):
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return self.__id <= other.binary
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return NotImplemented
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def __gt__(self, other: Any) -> bool:
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if isinstance(other, ObjectId):
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return self.__id > other.binary
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return NotImplemented
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def __ge__(self, other: Any) -> bool:
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if isinstance(other, ObjectId):
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return self.__id >= other.binary
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return NotImplemented
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def __hash__(self) -> int:
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"""Get a hash value for this :class:`ObjectId`."""
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return hash(self.__id)
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