objectid -- Tools for working with MongoDB ObjectIds#

Tools for working with MongoDB ObjectIds.

class bson.objectid.ObjectId(oid=None)#

Initialize a new ObjectId.

An ObjectId is a 12-byte unique identifier consisting of:

  • a 4-byte value representing the seconds since the Unix epoch,

  • a 5-byte random value,

  • a 3-byte counter, starting with a random value.

By default, ObjectId() creates a new unique identifier. The optional parameter oid can be an ObjectId, or any 12 bytes.

For example, the 12 bytes b'foo-bar-quux' do not follow the ObjectId specification but they are acceptable input:

>>> ObjectId(b'foo-bar-quux')
ObjectId('666f6f2d6261722d71757578')

oid can also be a str of 24 hex digits:

>>> ObjectId('0123456789ab0123456789ab')
ObjectId('0123456789ab0123456789ab')

Raises InvalidId if oid is not 12 bytes nor 24 hex digits, or TypeError if oid is not an accepted type.

Parameters:

  • oid (optional): a valid ObjectId.

参见

The MongoDB documentation on ObjectIds.

在 3.8 版本发生变更: ObjectId now implements the ObjectID specification version 0.2.

str(o)

Get a hex encoded version of ObjectId o.

The following property always holds:

>>> o = ObjectId()
>>> o == ObjectId(str(o))
True

This representation is useful for urls or other places where o.binary is inappropriate.

property binary: bytes#

12-byte binary representation of this ObjectId.

classmethod from_datetime(generation_time: datetime) → ObjectId#

Create a dummy ObjectId instance with a specific generation time.

This method is useful for doing range queries on a field containing ObjectId instances.

警告

It is not safe to insert a document containing an ObjectId generated using this method. This method deliberately eliminates the uniqueness guarantee that ObjectIds generally provide. ObjectIds generated with this method should be used exclusively in queries.

generation_time will be converted to UTC. Naive datetime instances will be treated as though they already contain UTC.

An example using this helper to get documents where "_id" was generated before January 1, 2010 would be:

>>> gen_time = datetime.datetime(2010, 1, 1)
>>> dummy_id = ObjectId.from_datetime(gen_time)
>>> result = collection.find({"_id": {"$lt": dummy_id}})
Parameters:

  • generation_time: datetime to be used as the generation time for the resulting ObjectId.

property generation_time: datetime#

A datetime.datetime instance representing the time of generation for this ObjectId.

The datetime.datetime is timezone aware, and represents the generation time in UTC. It is precise to the second.

classmethod is_valid(oid: Any) → bool#

Checks if a oid string is valid or not.

Parameters:

  • oid: the object id to validate

在 2.3 版本加入.