rxjs 5.5+ retryWhen not calling source observable?

Question

我觉得我在这里遗漏了一些非常简单的东西。我正在尝试为获取创建一个简单的重试，但只有 retryWhen 中的代码被执行。我正在使用 React，所以我没有 this.http.get 便利。也许这是 from(/*promise*/) 的问题？我试图将重试逻辑基于 this post.

这是我希望看到的：

Getting data from fetch...
In the retryWhen
In the interval
/* repeat the previous 3 lines 3x times including the Fetch */
Giving up

相反，我得到：

Getting data from fetch...
In the retryWhen
In the interval...
In the interval...
In the interval...
In the interval...
Giving up

所以它只是在重试时重复代码，而不是重复原来的 fetchData 调用。我可能遗漏了一些我的 RXJS 知识的基础知识。

测试代码如下：

const fetchData = new Promise((res, rej) => {
  console.log("Getting data from fetch...");
  rej(); // just fail immediately to test the retry
});

const source = from(fetchData)
  .pipe(
    retryWhen(_ => {
      console.log("In the retryWhen");
      return interval(1000).pipe(
        tap(_ => console.log("In the interval...")),
        flatMap(count => count == 3 ? throwError("Giving up") : of(count))
      )
    }));

source.subscribe(
  result => console.log(result),
  err => console.log(err)
);

Answer 1

更改下面的代码看看它是否有效。 retryWhen 传递给您一个错误流，如果有错误，它将继续发出。你 return 一个 timer 来指定 retryWhen 中每次重试之间的延迟。延迟后，它将为您重试可观察到的源

const fetchData = defer(() => new Promise((res, rej) => {
      console.log('in promise')
        rej("Failed to fetch data"); 
      // fail the first 2 times
    }) );

const source = fetchData.pipe(
  retryWhen(err => {
    let count = 0;
    console.log("In the retryWhen");
    return err.pipe(
      tap(_ => {
        count++;
        console.log("In the interval...");
      }),
      mergeMap(_ => (count == 2 ? throwError("Giving up") : timer(2000)))
    );
  })
);

source.subscribe(result => console.log(result), err => console.warn(err));

https://codepen.io/fancheung/pen/gqjawe

rxjs 5.5+ retryWhen not calling source observable?

rxjs 5.5+ retryWhen not calling source observable?

rxjs

observable

rxjs6

rxjs-pipeable-operators

retrywhen