21.20. uuid
— UUID objects according to RFC 4122¶
Source code: Lib/uuid.py
This module provides immutable UUID
objects (the UUID
class)
and the functions uuid1()
, uuid3()
, uuid4()
, uuid5()
for
generating version 1, 3, 4, and 5 UUIDs as specified in RFC 4122.
If all you want is a unique ID, you should probably call uuid1()
or
uuid4()
. Note that uuid1()
may compromise privacy since it creates
a UUID containing the computer’s network address. uuid4()
creates a
random UUID.
-
class
uuid.
UUID
(hex=None, bytes=None, bytes_le=None, fields=None, int=None, version=None)¶ Create a UUID from either a string of 32 hexadecimal digits, a string of 16 bytes as the bytes argument, a string of 16 bytes in little-endian order as the bytes_le argument, a tuple of six integers (32-bit time_low, 16-bit time_mid, 16-bit time_hi_version, 8-bit clock_seq_hi_variant, 8-bit clock_seq_low, 48-bit node) as the fields argument, or a single 128-bit integer as the int argument. When a string of hex digits is given, curly braces, hyphens, and a URN prefix are all optional. For example, these expressions all yield the same UUID:
UUID('{12345678-1234-5678-1234-567812345678}') UUID('12345678123456781234567812345678') UUID('urn:uuid:12345678-1234-5678-1234-567812345678') UUID(bytes=b'\x12\x34\x56\x78'*4) UUID(bytes_le=b'\x78\x56\x34\x12\x34\x12\x78\x56' + b'\x12\x34\x56\x78\x12\x34\x56\x78') UUID(fields=(0x12345678, 0x1234, 0x5678, 0x12, 0x34, 0x567812345678)) UUID(int=0x12345678123456781234567812345678)
Exactly one of hex, bytes, bytes_le, fields, or int must be given. The version argument is optional; if given, the resulting UUID will have its variant and version number set according to RFC 4122, overriding bits in the given hex, bytes, bytes_le, fields, or int.
Comparison of UUID objects are made by way of comparing their
UUID.int
attributes. Comparison with a non-UUID object raises aTypeError
.str(uuid)
returns a string in the form12345678-1234-5678-1234-567812345678
where the 32 hexadecimal digits represent the UUID.
UUID
instances have these read-only attributes:
-
UUID.
bytes
¶ The UUID as a 16-byte string (containing the six integer fields in big-endian byte order).
-
UUID.
bytes_le
¶ The UUID as a 16-byte string (with time_low, time_mid, and time_hi_version in little-endian byte order).
-
UUID.
fields
¶ A tuple of the six integer fields of the UUID, which are also available as six individual attributes and two derived attributes:
Field Meaning time_low
the first 32 bits of the UUID time_mid
the next 16 bits of the UUID time_hi_version
the next 16 bits of the UUID clock_seq_hi_variant
the next 8 bits of the UUID clock_seq_low
the next 8 bits of the UUID node
the last 48 bits of the UUID time
the 60-bit timestamp clock_seq
the 14-bit sequence number
-
UUID.
hex
¶ The UUID as a 32-character hexadecimal string.
-
UUID.
int
¶ The UUID as a 128-bit integer.
-
UUID.
urn
¶ The UUID as a URN as specified in RFC 4122.
-
UUID.
variant
¶ The UUID variant, which determines the internal layout of the UUID. This will be one of the constants
RESERVED_NCS
,RFC_4122
,RESERVED_MICROSOFT
, orRESERVED_FUTURE
.
The uuid
module defines the following functions:
-
uuid.
getnode
()¶ Get the hardware address as a 48-bit positive integer. The first time this runs, it may launch a separate program, which could be quite slow. If all attempts to obtain the hardware address fail, we choose a random 48-bit number with its eighth bit set to 1 as recommended in RFC 4122. «Hardware address» means the MAC address of a network interface, and on a machine with multiple network interfaces the MAC address of any one of them may be returned.
-
uuid.
uuid1
(node=None, clock_seq=None)¶ Generate a UUID from a host ID, sequence number, and the current time. If node is not given,
getnode()
is used to obtain the hardware address. If clock_seq is given, it is used as the sequence number; otherwise a random 14-bit sequence number is chosen.
-
uuid.
uuid3
(namespace, name)¶ Generate a UUID based on the MD5 hash of a namespace identifier (which is a UUID) and a name (which is a string).
-
uuid.
uuid4
()¶ Generate a random UUID.
-
uuid.
uuid5
(namespace, name)¶ Generate a UUID based on the SHA-1 hash of a namespace identifier (which is a UUID) and a name (which is a string).
The uuid
module defines the following namespace identifiers for use with
uuid3()
or uuid5()
.
-
uuid.
NAMESPACE_DNS
¶ When this namespace is specified, the name string is a fully-qualified domain name.
-
uuid.
NAMESPACE_URL
¶ When this namespace is specified, the name string is a URL.
-
uuid.
NAMESPACE_OID
¶ When this namespace is specified, the name string is an ISO OID.
-
uuid.
NAMESPACE_X500
¶ When this namespace is specified, the name string is an X.500 DN in DER or a text output format.
The uuid
module defines the following constants for the possible values
of the variant
attribute:
-
uuid.
RESERVED_NCS
¶ Reserved for NCS compatibility.
-
uuid.
RESERVED_MICROSOFT
¶ Reserved for Microsoft compatibility.
-
uuid.
RESERVED_FUTURE
¶ Reserved for future definition.
Ver también
- RFC 4122 - A Universally Unique IDentifier (UUID) URN Namespace
- This specification defines a Uniform Resource Name namespace for UUIDs, the internal format of UUIDs, and methods of generating UUIDs.
21.20.1. Example¶
Here are some examples of typical usage of the uuid
module:
>>> import uuid
>>> # make a UUID based on the host ID and current time
>>> uuid.uuid1()
UUID('a8098c1a-f86e-11da-bd1a-00112444be1e')
>>> # make a UUID using an MD5 hash of a namespace UUID and a name
>>> uuid.uuid3(uuid.NAMESPACE_DNS, 'python.org')
UUID('6fa459ea-ee8a-3ca4-894e-db77e160355e')
>>> # make a random UUID
>>> uuid.uuid4()
UUID('16fd2706-8baf-433b-82eb-8c7fada847da')
>>> # make a UUID using a SHA-1 hash of a namespace UUID and a name
>>> uuid.uuid5(uuid.NAMESPACE_DNS, 'python.org')
UUID('886313e1-3b8a-5372-9b90-0c9aee199e5d')
>>> # make a UUID from a string of hex digits (braces and hyphens ignored)
>>> x = uuid.UUID('{00010203-0405-0607-0809-0a0b0c0d0e0f}')
>>> # convert a UUID to a string of hex digits in standard form
>>> str(x)
'00010203-0405-0607-0809-0a0b0c0d0e0f'
>>> # get the raw 16 bytes of the UUID
>>> x.bytes
b'\x00\x01\x02\x03\x04\x05\x06\x07\x08\t\n\x0b\x0c\r\x0e\x0f'
>>> # make a UUID from a 16-byte string
>>> uuid.UUID(bytes=x.bytes)
UUID('00010203-0405-0607-0809-0a0b0c0d0e0f')