Question

我尝试重复请求，直到响应有使用RxJS的数据，此时我想调用成功（或失败）处理程序，但我遇到了麻烦w / RxJS。这是我目前的做法：

// ... redux-observable action observable
.mergeMap(() =>
    fetchData()
    .repeatWhen(response =>
        response.takeWhile(({ data }) => !data.length)
        .of(response)
    )
)
.map(successFunction)
.catch(failureFunction);

免责声明：我对RxJS很新......

Answer 1

听起来你想要抑制ajax结果并重试，直到你得到你想要的响应。我是这样做的：

// observable that will re-fetch each time it is subscribed
const request = Observable.defer(() => fetchData());

// each time request produces its value, check the value
// and if it is not what you want, return the request
// observable, else return an observable with the response
// use switchMap() to then subscribe to the returned
// observable.
const requestWithRetry = request.switchMap(r =>
    r.data.length ? Observable.of(r) : requestWithRetry);

Answer 2

空数据不是错误，所以首先我们检查数据是否为空，如果是，则抛出错误。然后retryWhen可用于测试此错误，并在其发生时重试。

.mergeMap(() =>
   fetchData()
   .map(data => {
       if (!data.length) {
          throw 'no data';
       } 
       return data;
    })
   .retryWhen(errors => errors.takeWhile(error => error === 'no data'))
)
.map(successFunction)
.catch(failureFunction);

Answer 3

在一个间隔上重复请求，过滤其结果并采取一次发射更简单。

Observable.timer(0, 500)
  .flatMap(() => fetchData())
  .filter(r => r.data && r.data.length)
  .take(1)
  .timeout(10000)

http://jsbin.com/cafericore/1/edit?js,console

如何在RxJS Observable满足条件之前重复ajax请求？

3 个答案: