How to generate unique id in Dart

I write websocket chat. How to generate unique id for user?

now i use this code:

id = new DateTime.now().millisecondsSinceEpoch;

is there any more neat solution?

1. There is a UUID pub package:

http://pub.dartlang.org/packages/uuid

example usage:

import 'package:uuid/uuid.dart';

// Create uuid object
var uuid = Uuid();

// 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(uuid.NAMESPACE_URL, 'www.google.com'); // -> 'c74a196f-f19d-5ea9-bffd-a2742432fc9c'

2. This src has a dart GUID generator

https://github.com/MikeMitterer/AndroidIconGenerator.DART/blob/445884924/lib/src/model/communication/GUIDGen.dart

I'll not post the function src here directly as there is no apparent licence with it, but example usage is as follows:

final String uuid = GUIDGen.generate();

In year 2020 you can do UniqueKey(); which is a built in class:

https://api.flutter.dev/flutter/widgets/UniqueKey-class.html

Note

A key that is only equal to itself.

This cannot be created with a const constructor because that implies that all instantiated keys would be the same instance and therefore not be unique.

Besides from uuid, you can also try this to generate small unique keys:

https://pub.dev/packages/nanoid

They even have a collision calculator:

https://zelark.github.io/nano-id-cc/

If you like MongoDB style ids you could consider this small package that will help create the object id:

https://pub.dev/packages/crossplat_objectid

import 'package:bson_objectid/bson_objectid.dart';

main() {
  ObjectId id1 = new ObjectId();
  print(id1.toHexString());

  ObjectId id2 = new ObjectId.fromHexString('54495ad94c934721ede76d90');
  print(id2.timestamp);
  print(id2.machineId);
  print(id2.processId);
  print(id2.counter);
}

There is also https://pub.dev/packages/xid which is lock free and has a Unicity guaranteed for 16,777,216 (24 bits) unique ids per second and per host/process

import 'package:xid/xid.dart';

void main() {
  var xid = Xid();
  print('generated id: $xid');

}

I use microseconds instead of milliseconds, which is much more accurate and there is no need to add any package.

 String idGenerator() {
    final now = DateTime.now();
    return now.microsecondsSinceEpoch.toString();
  }