Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1 | :mod:`uuid` --- UUID objects according to RFC 4122 |
| 2 | ================================================== |
| 3 | |
| 4 | .. module:: uuid |
| 5 | :synopsis: UUID objects (universally unique identifiers) according to RFC 4122 |
| 6 | .. moduleauthor:: Ka-Ping Yee <ping@zesty.ca> |
| 7 | .. sectionauthor:: George Yoshida <quiver@users.sourceforge.net> |
| 8 | |
Terry Jan Reedy | fa089b9 | 2016-06-11 15:02:54 -0400 | [diff] [blame] | 9 | **Source code:** :source:`Lib/uuid.py` |
| 10 | |
| 11 | -------------- |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 12 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 13 | This module provides immutable :class:`UUID` objects (the :class:`UUID` class) |
| 14 | and the functions :func:`uuid1`, :func:`uuid3`, :func:`uuid4`, :func:`uuid5` for |
| 15 | generating version 1, 3, 4, and 5 UUIDs as specified in :rfc:`4122`. |
| 16 | |
| 17 | If all you want is a unique ID, you should probably call :func:`uuid1` or |
| 18 | :func:`uuid4`. Note that :func:`uuid1` may compromise privacy since it creates |
| 19 | a UUID containing the computer's network address. :func:`uuid4` creates a |
| 20 | random UUID. |
| 21 | |
Barry Warsaw | 8c130d7 | 2017-02-18 15:45:49 -0500 | [diff] [blame] | 22 | Depending on support from the underlying platform, :func:`uuid1` may or may |
| 23 | not return a "safe" UUID. A safe UUID is one which is generated using |
| 24 | synchronization methods that ensure no two processes can obtain the same |
| 25 | UUID. All instances of :class:`UUID` have an :attr:`is_safe` attribute |
| 26 | which relays any information about the UUID's safety, using this enumeration: |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 27 | |
Barry Warsaw | 8c130d7 | 2017-02-18 15:45:49 -0500 | [diff] [blame] | 28 | .. class:: SafeUUID |
| 29 | |
| 30 | .. versionadded:: 3.7 |
| 31 | |
| 32 | .. attribute:: SafeUUID.safe |
| 33 | |
| 34 | The UUID was generated by the platform in a multiprocessing-safe way. |
| 35 | |
| 36 | .. attribute:: SafeUUID.unsafe |
| 37 | |
| 38 | The UUID was not generated in a multiprocessing-safe way. |
| 39 | |
| 40 | .. attribute:: SafeUUID.unknown |
| 41 | |
| 42 | The platform does not provide information on whether the UUID was |
| 43 | generated safely or not. |
| 44 | |
| 45 | .. class:: UUID(hex=None, bytes=None, bytes_le=None, fields=None, int=None, version=None, *, is_safe=SafeUUID.unknown) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 46 | |
| 47 | Create a UUID from either a string of 32 hexadecimal digits, a string of 16 |
| 48 | bytes as the *bytes* argument, a string of 16 bytes in little-endian order as |
| 49 | the *bytes_le* argument, a tuple of six integers (32-bit *time_low*, 16-bit |
| 50 | *time_mid*, 16-bit *time_hi_version*, 8-bit *clock_seq_hi_variant*, 8-bit |
| 51 | *clock_seq_low*, 48-bit *node*) as the *fields* argument, or a single 128-bit |
| 52 | integer as the *int* argument. When a string of hex digits is given, curly |
| 53 | braces, hyphens, and a URN prefix are all optional. For example, these |
| 54 | expressions all yield the same UUID:: |
| 55 | |
| 56 | UUID('{12345678-1234-5678-1234-567812345678}') |
| 57 | UUID('12345678123456781234567812345678') |
| 58 | UUID('urn:uuid:12345678-1234-5678-1234-567812345678') |
Georg Brandl | 1d523e1 | 2009-12-19 18:23:28 +0000 | [diff] [blame] | 59 | UUID(bytes=b'\x12\x34\x56\x78'*4) |
| 60 | UUID(bytes_le=b'\x78\x56\x34\x12\x34\x12\x78\x56' + |
| 61 | b'\x12\x34\x56\x78\x12\x34\x56\x78') |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 62 | UUID(fields=(0x12345678, 0x1234, 0x5678, 0x12, 0x34, 0x567812345678)) |
| 63 | UUID(int=0x12345678123456781234567812345678) |
| 64 | |
| 65 | Exactly one of *hex*, *bytes*, *bytes_le*, *fields*, or *int* must be given. |
| 66 | The *version* argument is optional; if given, the resulting UUID will have its |
| 67 | variant and version number set according to RFC 4122, overriding bits in the |
| 68 | given *hex*, *bytes*, *bytes_le*, *fields*, or *int*. |
| 69 | |
Berker Peksag | 6b5e4a8 | 2016-12-31 20:08:16 +0300 | [diff] [blame] | 70 | Comparison of UUID objects are made by way of comparing their |
| 71 | :attr:`UUID.int` attributes. Comparison with a non-UUID object |
| 72 | raises a :exc:`TypeError`. |
| 73 | |
| 74 | ``str(uuid)`` returns a string in the form |
| 75 | ``12345678-1234-5678-1234-567812345678`` where the 32 hexadecimal digits |
| 76 | represent the UUID. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 77 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 78 | :class:`UUID` instances have these read-only attributes: |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 79 | |
| 80 | .. attribute:: UUID.bytes |
| 81 | |
| 82 | The UUID as a 16-byte string (containing the six integer fields in big-endian |
| 83 | byte order). |
| 84 | |
| 85 | |
| 86 | .. attribute:: UUID.bytes_le |
| 87 | |
| 88 | The UUID as a 16-byte string (with *time_low*, *time_mid*, and *time_hi_version* |
| 89 | in little-endian byte order). |
| 90 | |
| 91 | |
| 92 | .. attribute:: UUID.fields |
| 93 | |
| 94 | A tuple of the six integer fields of the UUID, which are also available as six |
| 95 | individual attributes and two derived attributes: |
| 96 | |
| 97 | +------------------------------+-------------------------------+ |
| 98 | | Field | Meaning | |
| 99 | +==============================+===============================+ |
| 100 | | :attr:`time_low` | the first 32 bits of the UUID | |
| 101 | +------------------------------+-------------------------------+ |
| 102 | | :attr:`time_mid` | the next 16 bits of the UUID | |
| 103 | +------------------------------+-------------------------------+ |
| 104 | | :attr:`time_hi_version` | the next 16 bits of the UUID | |
| 105 | +------------------------------+-------------------------------+ |
| 106 | | :attr:`clock_seq_hi_variant` | the next 8 bits of the UUID | |
| 107 | +------------------------------+-------------------------------+ |
| 108 | | :attr:`clock_seq_low` | the next 8 bits of the UUID | |
| 109 | +------------------------------+-------------------------------+ |
| 110 | | :attr:`node` | the last 48 bits of the UUID | |
| 111 | +------------------------------+-------------------------------+ |
| 112 | | :attr:`time` | the 60-bit timestamp | |
| 113 | +------------------------------+-------------------------------+ |
| 114 | | :attr:`clock_seq` | the 14-bit sequence number | |
| 115 | +------------------------------+-------------------------------+ |
| 116 | |
| 117 | |
| 118 | .. attribute:: UUID.hex |
| 119 | |
| 120 | The UUID as a 32-character hexadecimal string. |
| 121 | |
| 122 | |
| 123 | .. attribute:: UUID.int |
| 124 | |
| 125 | The UUID as a 128-bit integer. |
| 126 | |
| 127 | |
| 128 | .. attribute:: UUID.urn |
| 129 | |
| 130 | The UUID as a URN as specified in RFC 4122. |
| 131 | |
| 132 | |
| 133 | .. attribute:: UUID.variant |
| 134 | |
| 135 | The UUID variant, which determines the internal layout of the UUID. This will be |
Xiang Zhang | 8a17995 | 2017-01-10 11:29:27 +0800 | [diff] [blame] | 136 | one of the constants :const:`RESERVED_NCS`, :const:`RFC_4122`, |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 137 | :const:`RESERVED_MICROSOFT`, or :const:`RESERVED_FUTURE`. |
| 138 | |
| 139 | |
| 140 | .. attribute:: UUID.version |
| 141 | |
| 142 | The UUID version number (1 through 5, meaningful only when the variant is |
| 143 | :const:`RFC_4122`). |
| 144 | |
Barry Warsaw | 8c130d7 | 2017-02-18 15:45:49 -0500 | [diff] [blame] | 145 | .. attribute:: UUID.is_safe |
| 146 | |
| 147 | An enumeration of :class:`SafeUUID` which indicates whether the platform |
| 148 | generated the UUID in a multiprocessing-safe way. |
| 149 | |
| 150 | .. versionadded:: 3.7 |
| 151 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 152 | The :mod:`uuid` module defines the following functions: |
| 153 | |
| 154 | |
| 155 | .. function:: getnode() |
| 156 | |
| 157 | Get the hardware address as a 48-bit positive integer. The first time this |
| 158 | runs, it may launch a separate program, which could be quite slow. If all |
Barry Warsaw | 23df2d1 | 2017-11-28 17:26:04 -0500 | [diff] [blame^] | 159 | attempts to obtain the hardware address fail, we choose a random 48-bit |
| 160 | number with the multicast bit (least significant bit of the first octet) |
| 161 | set to 1 as recommended in RFC 4122. "Hardware address" means the MAC |
| 162 | address of a network interface. On a machine with multiple network |
| 163 | interfaces, universally administered MAC addresses (i.e. where the second |
| 164 | least significant bit of the first octet is *unset*) will be preferred over |
| 165 | locally administered MAC addresses, but with no other ordering guarantees. |
| 166 | |
| 167 | .. versionchanged:: 3.7 |
| 168 | Universally administered MAC addresses are preferred over locally |
| 169 | administered MAC addresses, since the former are guaranteed to be |
| 170 | globally unique, while the latter are not. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 171 | |
| 172 | .. index:: single: getnode |
| 173 | |
| 174 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 175 | .. function:: uuid1(node=None, clock_seq=None) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 176 | |
| 177 | Generate a UUID from a host ID, sequence number, and the current time. If *node* |
| 178 | is not given, :func:`getnode` is used to obtain the hardware address. If |
| 179 | *clock_seq* is given, it is used as the sequence number; otherwise a random |
| 180 | 14-bit sequence number is chosen. |
| 181 | |
| 182 | .. index:: single: uuid1 |
| 183 | |
| 184 | |
| 185 | .. function:: uuid3(namespace, name) |
| 186 | |
| 187 | Generate a UUID based on the MD5 hash of a namespace identifier (which is a |
| 188 | UUID) and a name (which is a string). |
| 189 | |
| 190 | .. index:: single: uuid3 |
| 191 | |
| 192 | |
| 193 | .. function:: uuid4() |
| 194 | |
| 195 | Generate a random UUID. |
| 196 | |
| 197 | .. index:: single: uuid4 |
| 198 | |
| 199 | |
| 200 | .. function:: uuid5(namespace, name) |
| 201 | |
| 202 | Generate a UUID based on the SHA-1 hash of a namespace identifier (which is a |
| 203 | UUID) and a name (which is a string). |
| 204 | |
| 205 | .. index:: single: uuid5 |
| 206 | |
| 207 | The :mod:`uuid` module defines the following namespace identifiers for use with |
| 208 | :func:`uuid3` or :func:`uuid5`. |
| 209 | |
| 210 | |
| 211 | .. data:: NAMESPACE_DNS |
| 212 | |
| 213 | When this namespace is specified, the *name* string is a fully-qualified domain |
| 214 | name. |
| 215 | |
| 216 | |
| 217 | .. data:: NAMESPACE_URL |
| 218 | |
| 219 | When this namespace is specified, the *name* string is a URL. |
| 220 | |
| 221 | |
| 222 | .. data:: NAMESPACE_OID |
| 223 | |
| 224 | When this namespace is specified, the *name* string is an ISO OID. |
| 225 | |
| 226 | |
| 227 | .. data:: NAMESPACE_X500 |
| 228 | |
| 229 | When this namespace is specified, the *name* string is an X.500 DN in DER or a |
| 230 | text output format. |
| 231 | |
| 232 | The :mod:`uuid` module defines the following constants for the possible values |
| 233 | of the :attr:`variant` attribute: |
| 234 | |
| 235 | |
| 236 | .. data:: RESERVED_NCS |
| 237 | |
| 238 | Reserved for NCS compatibility. |
| 239 | |
| 240 | |
| 241 | .. data:: RFC_4122 |
| 242 | |
| 243 | Specifies the UUID layout given in :rfc:`4122`. |
| 244 | |
| 245 | |
| 246 | .. data:: RESERVED_MICROSOFT |
| 247 | |
| 248 | Reserved for Microsoft compatibility. |
| 249 | |
| 250 | |
| 251 | .. data:: RESERVED_FUTURE |
| 252 | |
| 253 | Reserved for future definition. |
| 254 | |
| 255 | |
| 256 | .. seealso:: |
| 257 | |
| 258 | :rfc:`4122` - A Universally Unique IDentifier (UUID) URN Namespace |
| 259 | This specification defines a Uniform Resource Name namespace for UUIDs, the |
| 260 | internal format of UUIDs, and methods of generating UUIDs. |
| 261 | |
| 262 | |
| 263 | .. _uuid-example: |
| 264 | |
| 265 | Example |
| 266 | ------- |
| 267 | |
| 268 | Here are some examples of typical usage of the :mod:`uuid` module:: |
| 269 | |
| 270 | >>> import uuid |
| 271 | |
Ezio Melotti | b1b3fd2 | 2011-12-02 19:28:36 +0200 | [diff] [blame] | 272 | >>> # make a UUID based on the host ID and current time |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 273 | >>> uuid.uuid1() |
| 274 | UUID('a8098c1a-f86e-11da-bd1a-00112444be1e') |
| 275 | |
Ezio Melotti | b1b3fd2 | 2011-12-02 19:28:36 +0200 | [diff] [blame] | 276 | >>> # make a UUID using an MD5 hash of a namespace UUID and a name |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 277 | >>> uuid.uuid3(uuid.NAMESPACE_DNS, 'python.org') |
| 278 | UUID('6fa459ea-ee8a-3ca4-894e-db77e160355e') |
| 279 | |
Ezio Melotti | b1b3fd2 | 2011-12-02 19:28:36 +0200 | [diff] [blame] | 280 | >>> # make a random UUID |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 281 | >>> uuid.uuid4() |
| 282 | UUID('16fd2706-8baf-433b-82eb-8c7fada847da') |
| 283 | |
Ezio Melotti | b1b3fd2 | 2011-12-02 19:28:36 +0200 | [diff] [blame] | 284 | >>> # make a UUID using a SHA-1 hash of a namespace UUID and a name |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 285 | >>> uuid.uuid5(uuid.NAMESPACE_DNS, 'python.org') |
| 286 | UUID('886313e1-3b8a-5372-9b90-0c9aee199e5d') |
| 287 | |
Ezio Melotti | b1b3fd2 | 2011-12-02 19:28:36 +0200 | [diff] [blame] | 288 | >>> # make a UUID from a string of hex digits (braces and hyphens ignored) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 289 | >>> x = uuid.UUID('{00010203-0405-0607-0809-0a0b0c0d0e0f}') |
| 290 | |
Ezio Melotti | b1b3fd2 | 2011-12-02 19:28:36 +0200 | [diff] [blame] | 291 | >>> # convert a UUID to a string of hex digits in standard form |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 292 | >>> str(x) |
| 293 | '00010203-0405-0607-0809-0a0b0c0d0e0f' |
| 294 | |
Ezio Melotti | b1b3fd2 | 2011-12-02 19:28:36 +0200 | [diff] [blame] | 295 | >>> # get the raw 16 bytes of the UUID |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 296 | >>> x.bytes |
Georg Brandl | 1d523e1 | 2009-12-19 18:23:28 +0000 | [diff] [blame] | 297 | b'\x00\x01\x02\x03\x04\x05\x06\x07\x08\t\n\x0b\x0c\r\x0e\x0f' |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 298 | |
Ezio Melotti | b1b3fd2 | 2011-12-02 19:28:36 +0200 | [diff] [blame] | 299 | >>> # make a UUID from a 16-byte string |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 300 | >>> uuid.UUID(bytes=x.bytes) |
| 301 | UUID('00010203-0405-0607-0809-0a0b0c0d0e0f') |
| 302 | |