可观察的-将2个诺言转换为可观察的

本文介绍了可观察的-将2个诺言转换为可观察的的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我有一个流行的场景，我需要创建一个承诺，该承诺返回返回到第二个承诺的数据.如果第一个承诺失败，我需要取消第二个承诺.在承诺"土地上，它看起来像这样:

I have a popular scenario where I need to create one promise that returns data which is fed to a second promise.If the first promise fails, I need to cancel the second promise.In 'Promise' land it would look something like this:

Fn1.doPromise( initialData )
  .then(info => {
        Fn2.doPromise( info )
              .then(result => {
                  //success - return result
              })
              .catch(error => {
                //error
              });
  })
.catch(error => {
  //cancel 2nd promise and show error
});

现在，我正在尝试使用Observables和RxJS之类的方法来学习最佳方法.谁能给我一个好的解决方案?预先感谢！

Now I am trying to learn the best way to do this using Observables with something like RxJS. Can anyone give me a good solution ?Thank in advance !

推荐答案

RxJS处理错误的一般问题由此处.要点是:

The general issue of error handling with RxJS is dealt with here. Main points are :

捕获错误(使用catch运算符，无论是在实例级别还是在类级别)
使用onErrorResumeNext
重试序列(使用retry)
确保清理(使用finally)
确保资源处置(使用finally或using)
延迟错误(使用mergeDelayError)

Catching Errors (with catch operator, either at instance level or at class level)
Ignoring Errors with onErrorResumeNext
Retrying Sequences (with retry)
Ensuring Cleanup (with finally)
Ensuring Resource Disposal (with finally or using)
Delaying Errors (with mergeDelayError)

关于您的特定问题，您可以使用 Rx.Observable.fromPromise 将诺言转换为可观察的； Rx.Observable.prototype.catch 在发生错误时及时捕获.

About your specific question you can use Rx.Observable.fromPromise to convert a promise into an observable; Rx.Observable.prototype.catch to catch errors as they occur.

Rx.Observable.fromPromise(Fn1.doPromise( initialData ))
  .flatMap(info => {
        return Rx.Observable.fromPromise(Fn2.doPromise( info ))
              .flatMap(result => {
                  //success - return result
                  // !! You must return an observable or a promise here !!
              })
              .catch(error => {
                //error
                // !! You must return an observable here !!
              });
  })
.catch(error => {
  //cancel 2nd promise and show error
  // !! You must return an observable here !!
});

示例:

第一个错误处理程序已激活
没有错误
内部错误处理程序已激活

first error handler activated
no error
inner error handler activated

这篇关于可观察的-将2个诺言转换为可观察的的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！

retry