RxJS - 发生错误时 observable 不会完成 [英] RxJS - observable doesn't complete when an error occurs

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.`

An Observable may make zero or more OnNext notifications, each representing a single emitted item, and it may then follow those emission notifications by either an OnCompleted or an OnError notification, but not both. Upon issuing an OnCompleted or OnError notification, it may not thereafter issue any further notifications.`

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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