uuid

uuid

Version 4.x.x is a complete redesign of the underlying setup, but tries to be API compatible or similar to 3.x.

Simple, fast generation of RFC4122 and RFC9562 UUIDs.

Features:

• Generate RFC4122 version 1, version 4, or version 5 UUIDs
• Supports RFC9562 version 6, version 7, and version 8
• Optional monotonic version 7 generator
• Runs in web, server, and flutter
• Cryptographically strong random number generation on all platforms
• Validate and parse generic 128-bit hexadecimal values without enforcing UUID version or variant bits
• Documentation

Getting Started

Instructions

1. Open a command line and cd to your projects root folder
2. In your pubspec, add an entry for dart-uuid to your dependencies (example below)
3. pub install
4. If you wish to run tests, go into packages/dart-uuid/ and run 'dart test'

Pubspec

dependencies:
  uuid: ^4.6.0

import 'package:uuid/uuid.dart';

var uuid = Uuid();

Then create some ids ...

// Generate a v1 (time-based) id
uuid.v1(); // -> '6c84fb90-12c4-11e1-840d-7b25c5ee775a'

// Generate a v4 (random) id
uuid.v4(); // -> '110ec58a-a0f2-4ac4-8393-c866d813b8d1'

// Generate a v5 (namespace-name-sha1-based) id
uuid.v5(Namespace.url.value, 'www.google.com'); // -> 'c74a196f-f19d-5ea9-bffd-a2742432fc9c'

Structural 128-bit parsing

Use the explicit format APIs when the input must be a 128-bit hexadecimal value but UUID version and variant bits should not be enforced.

const value = '019f13f5-53cb-b219-ca3e-4b569376f32b';

Uuid.isValidUUIDFormat(fromString: value); // true
Uuid.parseHex128(value); // 16 bytes

const withoutDashes = '019f13f553cbb219ca3e4b569376f32b';
Uuid.parseHex128(withoutDashes, noDashes: true); // 16 bytes

Monotonic v7

uuid.v7() fills everything after the millisecond timestamp with random bits, so ids created in the same millisecond have no defined order. UuidV7Monotonic replaces the most significant of those random bits with a 16-bit counter (RFC 9562 §6.2, Method 1), so ids from one generator sort in creation order under an ordinary string comparison (or byte comparison if parsed).

import 'package:uuid/uuid.dart';
import 'package:uuid/v7monotonic.dart';

// Plain v7, both created in the same millisecond. Creation order and sort
// order happen to disagree.
const uuid = Uuid();
uuid.v7(); // -> '019fcd85-9fac-7f64-8711-97a4665f1adc'
uuid.v7(); // -> '019fcd85-9fac-715d-80d0-556404fa23ea'

// Monotonic, also within one millisecond. The counter defines the order.
final generator = UuidV7Monotonic();
generator.generate(); // -> '019fcd85-9fb3-7488-a625-f7a830c2dcf7'
generator.generate(); // -> '019fcd85-9fb3-7488-a87c-0c31456d733b'

Import the generator directly; it is not exported from uuid.dart.

Some limits of the monotonic generator:

1. Ordering only holds within one generator instance. v7 cannot order concurrent generators against each other without shared state.
2. Ids strictly increase unless the clock moves backward by more than 10 seconds, which resets ordering to the new clock reading. Ids stay unique across the reset.
3. Ids are not secret tokens. The counter increments by exactly +1 within a millisecond, so an observer holding one id can predict the next. Use v4 if unguessability matters.

Documentation

For documentation, please visit the Documentation page. Examples are included for most functions and classes.

For more complex examples and other usages, please look at the tests.

Release notes

See CHANGELOG