如何从rxjs中的错误中恢复? [英] How to recover from errors in rxjs?

问题描述

我试图了解如何使用可观察的序列以及如何从错误中恢复.

I'm trying to understand how to consume observable sequences and how to recover from errors.

我的示例有些人为，但是我的实际实现太复杂了，无法在此处显示.无论如何，我有someObservable，当用户单击UI时会发出值.这应该触发对API的请求(GET/POST/etc).问题在于，如果API返回错误，此后将不再调用postData.

My example is a bit contrived but my real implementation is a bit too complex to show here. Anyway, I have someObservable that emits values when the user clicks in the UI. This should trigger a request to the API (GET/POST/etc). The problem is that if the API returns an error, postData isn't called anymore after that.

我在这里举一个例子来说明问题.我发现我可以使用Rx.Observable.of而不是Rx.Observable.throw来保持运行.但这将向subscribe函数发出一个值.在我的实际应用程序中，postData是一项服务，该服务可以被应用程序的多个部分重用，并且我不确定是否要在其中使用of而不是throw.

I've make an example here that shows the problem. I've found that I can use Rx.Observable.of instead of Rx.Observable.throw to keep things running. But that will emit a value to the subscribe function. And in my real application postData is a service that is reused by multiple parts of the application and I'm not sure that I want to use of instead of throw there.

所以我的问题是，您通常如何处理此类事情?

So my question is, how do you normally handle things like these?

let someObservable = Rx.Observable.timer(1, 1000);

someObservable
.switchMap(data =>  {
  return postData(data);
})
.catch(error => {
  console.log("POST failed");
})
.subscribe(val => console.log("Success: " + val));

function postData(data) {
  console.log("Will post " + data);

  if (data !== 2) {
    return Rx.Observable.of(true);
  }
  else {
    return Rx.Observable.throw(new Error("400 Bad Request or something"));
  }
}

http://jsbin.com/naroyeyive/3/edit?js,console

推荐答案

如果要再次发送请求，则可能要查看retry和retryWhen而不是catch.

If you want to send the request again, you may want to look into retry and retryWhen instead of catch.

catch将使用返回的Observable作为新的源". 请参阅此bin以获取示例.

catch will use the returned Observable as new "source". See this bin for an example.

retry(When)将根据您传递给操作员的配置，在发生错误时重新订阅".您可以在此处找到示例和更多信息: https://www.learnrxjs.io/operators /error_handling/retrywhen.html

retry(When) will "re-subscribe" whenever an error occurs, based on the configuration you pass to the operators. You can find examples and more information here: https://www.learnrxjs.io/operators/error_handling/retrywhen.html

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