CODEWITHSUNDEEP
flutterdart
Joey Yi Zhao
Joey Yi Zhao

Reputation: 42426

How can I return a Future from a stream listen callback?

I have below code in flutter:

getData() {
  final linksStream = getLinksStream().listen((String uri) async {
     return uri;   
  });
}

In getData method, I want to return the value of uri which is from a stream listener. Since this value is generated at a later time, I am thinking to response a Future object in getData method. But I don't know how I can pass the uri as the value of Future. In javascript, I can simply create a promise and resolve the value uri. How can I achieve it in dart?

Upvotes: 3

Views: 2890

Answers (2)

Piotr Temp
Piotr Temp

Reputation: 435

In your code 'return uri' is not returning from getData but returning from anonymous function which is parameter of listen. Correct code is like:

Future<String> getData() {
  final Completer<String> c = new Completer<String>();
  final linksStream = getLinksStream().listen((String uri) {
     c.complete(uri);   
  });
  return c.future;
}

Upvotes: 6

Josteve Adekanbi
Josteve Adekanbi

Reputation: 12673

Try this

Future<String> getData() async{
  final linksStream = await getLinksStream().toList();
  return linksStream[0].toString();
}

Upvotes: 0

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