Question

I have a function that gets executed at certain intervals with some data. Something similar to a polling function:

function poll(handler) {
  setInterval(handler, 1000);  // Mocking network communication
}

So I want to use that function in a redux-observable epic like this (pseudocode to follow):

action$
  .filter(...)
  .map((action) => poll)
  .map(results from poll)

How can I subscribe to the polling function and use rxjs?

EDIT:

What I've tried but it's failing

function start() {
  return Rx.Observable.create((observer) => poll(observer.next));
}


function startProcess(action$) {
  return action$
    .filter((action) => action.type === 'START_PROCESS')
    .map((action) => start())
    .swipWhile((result) => result !== 'proceed')  // I only want to dispatch the next action after we get a `proceed` result from the polling function
    .map(() => ({ type: 'CAN_START_PROCESS' })
}

I could wrapp the poll function into a promise, and then using Rx.Observable.fromPromise but I'd like to do it the reactive way.

Answer 1

我建议你做的是写一个poll函数来返回一个observable：

function createPoll$() {
  return Rx.Observable.interval(1000)
    .flatMap(makeRequest);
}

您的启动过程功能如下：

function startProcess(action$) {
  return action$
    .filter((action) => action.type === 'START_PROCESS')
    .switchMap(createPoll$)
    .filter(result => result === 'proceed') 
    .map(() => ({ type: 'CAN_START_PROCESS' })
}

Answer 2

好的，我让它将观察者绑定到自身：

function start() {
  return Rx.Observable.create((observer) => poll(observer.next.bind(observer));
}

但是仍然不知道使用已经创建的运算符是否有更好的解决方案。

Create observable from polling function

2 个答案: