uuid — UUID objects according toRFC 9562¶

Source code:Lib/uuid.py

This module provides immutableUUID objects (theUUID class)andfunctions for generating UUIDs correspondingto a specific UUID version as specified inRFC 9562 (which supersedesRFC 4122),for example,uuid1() for UUID version 1,uuid3() for UUID version 3, and so on.Note that UUID version 2 is deliberately omitted as it is outside the scope of the RFC.

If all you want is a unique ID, you should probably calluuid1() oruuid4(). Note thatuuid1() may compromise privacy since it createsa UUID containing the computer’s network address.uuid4() creates arandom UUID.

Depending on support from the underlying platform,uuid1() may or maynot return a “safe” UUID. A safe UUID is one which is generated usingsynchronization methods that ensure no two processes can obtain the sameUUID. All instances ofUUID have anis_safe attributewhich relays any information about the UUID’s safety, using this enumeration:

classuuid.SafeUUID¶

Added in version 3.7.

safe¶

The UUID was generated by the platform in a multiprocessing-safe way.

unsafe¶

The UUID was not generated in a multiprocessing-safe way.

unknown¶

The platform does not provide information on whether the UUID wasgenerated safely or not.

classuuid.UUID(hex=None,bytes=None,bytes_le=None,fields=None,int=None,version=None,*,is_safe=SafeUUID.unknown)¶

Create a UUID from either a string of 32 hexadecimal digits, a string of 16bytes in big-endian order as thebytes argument, a string of 16 bytes inlittle-endian order as thebytes_le argument, a tuple of six integers(32-bittime_low, 16-bittime_mid, 16-bittime_hi_version,8-bitclock_seq_hi_variant, 8-bitclock_seq_low, 48-bitnode) as thefields argument, or a single 128-bit integer as theint argument.When a string of hex digits is given, curly braces, hyphens,and a URN prefix are all optional. For example, theseexpressions 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 ofhex,bytes,bytes_le,fields, orint must be given.Theversion argument is optional; if given, the resulting UUID will have itsvariant and version number set according toRFC 9562, overriding bits in thegivenhex,bytes,bytes_le,fields, orint.

Comparison of UUID objects are made by way of comparing theirUUID.int attributes. Comparison with a non-UUID objectraises aTypeError.

str(uuid) returns a string in the form12345678-1234-5678-1234-567812345678 where the 32 hexadecimal digitsrepresent 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-endianbyte order).

UUID.bytes_le¶

The UUID as a 16-byte string (withtime_low,time_mid, andtime_hi_versionin little-endian byte order).

UUID.fields¶

A tuple of the six integer fields of the UUID, which are also available as sixindividual attributes and two derived attributes:

UUID.hex¶

The UUID as a 32-character lowercase hexadecimal string.

UUID.int¶

The UUID as a 128-bit integer.

UUID.urn¶

The UUID as a URN as specified inRFC 9562.

UUID.variant¶

The UUID variant, which determines the internal layout of the UUID. This will beone of the constantsRESERVED_NCS,RFC_4122,RESERVED_MICROSOFT, orRESERVED_FUTURE.

UUID.version¶

The UUID version number (1 through 8, meaningful only when the variant isRFC_4122).

Changed in version 3.14:Added UUID versions 6, 7 and 8.

UUID.is_safe¶

An enumeration ofSafeUUID which indicates whether the platformgenerated the UUID in a multiprocessing-safe way.

Added in version 3.7.

Theuuid module defines the following functions:

uuid.getnode()¶

Get the hardware address as a 48-bit positive integer. The first time thisruns, it may launch a separate program, which could be quite slow. If allattempts to obtain the hardware address fail, we choose a random 48-bitnumber with the multicast bit (least significant bit of the first octet)set to 1 as recommended inRFC 4122. “Hardware address” means the MACaddress of a network interface. On a machine with multiple networkinterfaces, universally administered MAC addresses (i.e. where the secondleast significant bit of the first octet isunset) will be preferred overlocally administered MAC addresses, but with no other ordering guarantees.

Changed in version 3.7:Universally administered MAC addresses are preferred over locallyadministered MAC addresses, since the former are guaranteed to beglobally unique, while the latter are not.

uuid.uuid1(node=None,clock_seq=None)¶

Generate a UUID from a host ID, sequence number, and the current timeaccording toRFC 9562, §5.1.

Whennode is not specified,getnode() is used to obtain the hardwareaddress as a 48-bit positive integer. When a sequence numberclock_seq isnot specified, a pseudo-random 14-bit positive integer is generated.

Ifnode orclock_seq exceed their expected bit count,only their least significant bits are kept.

uuid.uuid3(namespace,name)¶

Generate a UUID based on the MD5 hash of a namespace identifier (which is aUUID) and a name (which is abytes object or a stringthat will be encoded using UTF-8)according toRFC 9562, §5.3.

uuid.uuid4()¶

Generate a random UUID in a cryptographically-secure methodaccording toRFC 9562, §5.4.

uuid.uuid5(namespace,name)¶

Generate a UUID based on the SHA-1 hash of a namespace identifier (which is aUUID) and a name (which is abytes object or a stringthat will be encoded using UTF-8)according toRFC 9562, §5.5.

uuid.uuid6(node=None,clock_seq=None)¶

Generate a UUID from a sequence number and the current time according toRFC 9562, §5.6.

This is an alternative touuid1() to improve database locality.

Whennode is not specified,getnode() is used to obtain the hardwareaddress as a 48-bit positive integer. When a sequence numberclock_seq isnot specified, a pseudo-random 14-bit positive integer is generated.

Ifnode orclock_seq exceed their expected bit count,only their least significant bits are kept.

Added in version 3.14.

uuid.uuid7()¶

Generate a time-based UUID according toRFC 9562, §5.7.

For portability across platforms lacking sub-millisecond precision, UUIDsproduced by this function embed a 48-bit timestamp and use a 42-bit counterto guarantee monotonicity within a millisecond.

Added in version 3.14.

uuid.uuid8(a=None,b=None,c=None)¶

Generate a pseudo-random UUID according toRFC 9562, §5.8.

When specified, the parametersa,b andc are expected to bepositive integers of 48, 12 and 62 bits respectively. If they exceedtheir expected bit count, only their least significant bits are kept;non-specified arguments are substituted for a pseudo-random integer ofappropriate size.

By default,a,b andc are not generated by a cryptographicallysecure pseudo-random number generator (CSPRNG). Useuuid4() whena UUID needs to be used in a security-sensitive context.

Added in version 3.14.

Theuuid module defines the following namespace identifiers for use withuuid3() oruuid5().

uuid.NAMESPACE_DNS¶

When this namespace is specified, thename string is a fully qualified domainname.

uuid.NAMESPACE_URL¶

When this namespace is specified, thename string is a URL.

uuid.NAMESPACE_OID¶

When this namespace is specified, thename string is an ISO OID.

uuid.NAMESPACE_X500¶

When this namespace is specified, thename string is an X.500 DN in DER or atext output format.

Theuuid module defines the following constants for the possible valuesof thevariant attribute:

uuid.RESERVED_NCS¶

Reserved for NCS compatibility.

uuid.RFC_4122¶

Specifies the UUID layout given inRFC 4122. This constant is keptfor backward compatibility even thoughRFC 4122 has been supersededbyRFC 9562.

uuid.RESERVED_MICROSOFT¶

Reserved for Microsoft compatibility.

uuid.RESERVED_FUTURE¶

Reserved for future definition.

Theuuid module defines the special Nil and Max UUID values:

uuid.NIL¶

A special form of UUID that is specified to have all 128 bits set to zeroaccording toRFC 9562, §5.9.

Added in version 3.14.

uuid.MAX¶

A special form of UUID that is specified to have all 128 bits set to oneaccording toRFC 9562, §5.10.

Added in version 3.14.

python-muuid[-h][-u{uuid1,uuid3,uuid4,uuid5,uuid6,uuid7,uuid8}][-nNAMESPACE][-NNAME]

>>>importuuid>>># 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.bytesb'\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')>>># get the Nil UUID>>>uuid.NILUUID('00000000-0000-0000-0000-000000000000')>>># get the Max UUID>>>uuid.MAXUUID('ffffffff-ffff-ffff-ffff-ffffffffffff')>>># same as UUIDv1 but with fields reordered to improve DB locality>>>uuid.uuid6()UUID('1f0799c0-98b9-62db-92c6-a0d365b91053')>>># get UUIDv7 creation (local) time as a timestamp in milliseconds>>>u=uuid.uuid7()>>>u.time1743936859822>>># get UUIDv7 creation (local) time as a datetime object>>>importdatetimeasdt>>>dt.datetime.fromtimestamp(u.time/1000)datetime.datetime(...)>>># make a UUID with custom blocks>>>uuid.uuid8(0x12345678,0x9abcdef0,0x11223344)UUID('00001234-5678-8ef0-8000-000011223344')

# generate a random UUID - by default uuid4() is used$python-muuid# generate a UUID using uuid1()$python-muuid-uuuid1# generate a UUID using uuid5$python-muuid-uuuid5-n@url-Nexample.com# generate 42 random UUIDs$python-muuid-C42