如何在Dart中使用StreamZip合并流 [英] How to merge stream using StreamZip in Dart

问题描述

我有两个流:

Stream<List<Order>>  stream1 = pendingStream();
Stream<List<Order>>  stream2 = preparingStream();

我正在尝试使用 package:async/async.dart 包中的 StreamZip 像这样合并流...

I'm trying to use StreamZip from the package:async/async.dart package to merge the streams like so...

Stream<List<Order>> getData() {
     Stream<List<Order>>  stream1 = pendingStream();
     Stream<List<Order>>  stream2 = preparingStream();
    return StreamZip([stream1, stream2]);
}

但是它不会编译.说:

The element type 'Stream<List<Order>>' can't be assigned to the list type 'Stream<Order>'.

据我了解，StreamZip应该接受两个流?我有什么不对吗?

From what I understand StreamZip should accept the two streams? What am I dong wrong?

推荐答案

您正在创建一个 StreamZip< T> ，它将为每个事件发出一个 List< T> 您可以在文档中引用.

You are creating a StreamZip<T> which will emit a List<T> of each event of its merged streams as you can refer in the documentation.

每个合并的流都发出 List< Order> 类型，这意味着您将创建一个合并的流，该合并的流将发出 List的 List .

Each of your merged streams emit a List<Order> type, so that means that you will create a merged stream that will emit a List of List.

基本上，您只需要将返回类型从 Stream< List< Order>> 更改为 Stream< List< List< Order>> .

Basically, you only need to change your return type from Stream<List<Order>> to Stream<List<List<Order>>>.

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