CODEWITHSUNDEEP
dartsingletonangular
Andrea Bozza
Andrea Bozza

Reputation: 1384

injection in a Dart singleton with angular2

Hi have this singleton class:

class Singleton {
  static final Singleton _singleton = new Singleton._internal();

  factory Singleton() {
    return _singleton;
  }

  Singleton._internal();
}

i want to inject a Logger inside my class in this way:

class Singleton {
  static final Singleton _singleton = new Singleton._internal();

  factory Singleton( @Inject(LoggerService) this.log) {
    return _singleton;
  }

  Singleton._internal();
}

but it seem that Factory doesn't not support the injection.

Upvotes: 2

Views: 507

Answers (1)

Günter Zöchbauer
Günter Zöchbauer

Reputation: 658027

In my opinion this is the wrong approach in Angular. Angular DI provides singletons by itself.

class Singleton {
  final LoggerService log;

  Singleton(this.log);
}

bootstrap(AppComponent, [LoggerService, Singleton]);

should do what you want. As long as you don't add Singleton to providers elsewhere (for example on a component) Angular2 will always inject the same instance.

If you still want to keep above pattern, use

bootstrap(AppComponent, [
    LoggerService, 
    provide(Singleton, 
        useFactory: (log) => new Singleton(log), 
        deps: [LoggerService])
]);

Upvotes: 2

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