CODEWITHSUNDEEP
flutterdart
Alexandr Pashkevich
Alexandr Pashkevich

Reputation: 1

Return result from inner stream listen DART

I need to return result from function if stream returns no connection value.

So i have outer function and inner function. How can i return result from outer inside inner?

Future<bool> send() async {

        var subscription = Connectivity().onConnectivityChanged.listen((ConnectivityResult result) {

            if(result == ConnectivityResult.none)
                throw("No connectivity");
// Need to stop `send` function here and return some result
        });

        await doSomeWork();

        return true;
}

Upvotes: 0

Views: 1337

Answers (1)

Nate Bosch
Nate Bosch

Reputation: 10935

The Future returned by send can only be completed once, while the Stream may have multiple events emitted - you can't complete it with true and then later complete again with false because some new event came through the stream.

You could decide that the return value from send depends on the first event in the stream:

Future<bool> send() async {
  var result = await Connectivity().onConnectivityChange.first;
  if (result == ConnectivityResult.none) {
    // handle no connection
    return false;
  }
  await doSomeWork(); // only happens if the first result was not `none`
  return true;
}

Or you'll need to make a decision on what it means for a none connectivity result to come through after doSomeWork() was already called and the Future returned from send already completed.

Upvotes: 3

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