whenComplete method

  1. @override
Future<T> whenComplete (
  1. FutureOr action(
      )
    )
    override

    Registers a function to be called when this future completes.

    The action function is called when this future completes, whether it does so with a value or with an error.

    This is the asynchronous equivalent of a "finally" block.

    The future returned by this call, f, will complete the same way as this future unless an error occurs in the action call, or in a Future returned by the action call. If the call to action does not return a future, its return value is ignored.

    If the call to action throws, then f is completed with the thrown error.

    If the call to action returns a Future, f2, then completion of f is delayed until f2 completes. If f2 completes with an error, that will be the result of f too. The value of f2 is always ignored.

    This method is equivalent to:

    Future<T> whenComplete(action()) {
      return this.then((v) {
        var f2 = action();
        if (f2 is Future) return f2.then((_) => v);
        return v
      }, onError: (e) {
        var f2 = action();
        if (f2 is Future) return f2.then((_) { throw e; });
        throw e;
      });
    }
    

    Implementation

    @override
    Future<T> whenComplete(FutureOr Function() action) =>
        _future.whenComplete(action);