The MongoDB\BSON\ObjectId class
(mongodb >=1.0.0)
Introduction
BSON type for an » ObjectId. The value consists of 12 bytes, where the first four bytes are a timestamp that reflect the ObjectId's creation. Specifically, the value consists of:
- a 4-byte value representing the seconds since the Unix epoch,
- a 3-byte machine identifier,
- a 2-byte process ID, and
- a 3-byte counter, starting with a random value.
In MongoDB, each document stored in a collection requires a unique _id field that acts as a primary key. If an inserted document omits the _id field, the driver automatically generates an ObjectId for the _id field.
Using ObjectIds for the _id field provides the following additional benefits:
- The creation time of the ObjectId may be accessed using the MongoDB\BSON\ObjectId::getTimestamp() method.
- Sorting on an _id field that stores ObjectId values is roughly equivalent to sorting by creation time.
Class synopsis
Changelog
Version | Description |
---|---|
1.3.0 |
Renamed from MongoDB\BSON\ObjectID to MongoDB\BSON\ObjectId. |
1.2.0 | Implements Serializable and JsonSerializable. |
Table of Contents
- MongoDB\BSON\ObjectId::__construct — Construct a new ObjectId
- MongoDB\BSON\ObjectId::getTimestamp — Returns the timestamp component of this ObjectId
- MongoDB\BSON\ObjectId::jsonSerialize — Returns a representation that can be converted to JSON
- MongoDB\BSON\ObjectId::serialize — Serialize an ObjectId
- MongoDB\BSON\ObjectId::__toString — Returns the hexidecimal representation of this ObjectId
- MongoDB\BSON\ObjectId::unserialize — Unserialize an ObjectId
English translation
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Document created the 30/01/2003, last modified the 26/10/2018
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References
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