RxJS - 发生错误时 observable 不会完成

问题描述

当我从头开始创建一个 observable 并且有观察者错误，然后完成时，订阅的完成部分永远不会被调用.

When I create an observable from scratch, and have the observer error, then complete, the done part of the subscription never is invoked.

var observer = Rx.Observable.create(function(observer){
    observer.onError(new Error('no!'));
    observer.onCompleted();
})

observer.subscribe(
    function(x) { console.log('succeeded with ' + x ) },
    function(x) { console.log('errored with ' + x ) },
    function() { console.log('completed') }
)

输出为:

errored with Error: no!

我希望它是:

errored with Error: no!
completed

如果我更改代码以调用 onNext 而不是 onError，observable 将正确完成:

If I change the code to invoke onNext instead of onError, the observable properly completes:

var observer = Rx.Observable.create(function(observer){
    observer.onNext('Hi!');
    observer.onCompleted();
})

observer.subscribe(
    function(x) { console.log('succeeded with ' + x ) },
    function(x) { console.log('errored with ' + x ) },
    function() { console.log('completed') }
)

我得到了预期的输出:

succeeded with Hi!
completed

为什么发生错误时它没有完成?

Why does it not complete when an error has occured?

推荐答案

那是因为错误意味着完成，所以与 onCompleted 关联的回调永远不会被调用.您可以在此处查看可观察的 Rxjs 合同(http://reactivex.io/documentation/contract.html) :

That's because an error means completion, so the callback associated to onCompleted never gets called. You can review here Rxjs contract for observables (http://reactivex.io/documentation/contract.html) :

一个 Observable 可以发出零个或多个 OnNext 通知，每个通知代表一个发出的项目，然后它可以通过 OnCompleted 或 OnError 通知跟随这些发出通知，但不能同时发出这两个通知.在发出 OnCompleted 或 OnError 通知后，它可能不会发出任何进一步的通知.`

对于错误管理，您可以查看:https://github.com/Reactive-Extensions/RxJS/blob/master/doc/gettingstarted/errors.md

For error management, you can have a look at :https://github.com/Reactive-Extensions/RxJS/blob/master/doc/gettingstarted/errors.md

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