代码之家 › 专栏 › 技术社区 › Lukasz 'Severiaan' Grela

如何循环epic呼叫

rxjs6 redux-observable polling react-redux reactjs

1

Lukasz 'Severiaan' Grela · 技术社区 · 6 年前

我有以下几点:

import {
  map,
  catchError,
  switchMap,
  takeUntil,
} from 'rxjs/operators';
import {
  FETCH_JOKES,
  jokesReceived,
  FETCH_JOKES_CANCELLED,
  jokesFetchFailed,
} from '../actions/jokes-action';
import { ofType } from 'redux-observable';
import { of, concat } from 'rxjs';
import { ajax } from 'rxjs/ajax';

const getJokes = () =>
  ajax.getJSON('http://api.icndb.com/jokes/random?escape=javascript');

const fetchJokesEpic = action$ => {
  return action$.pipe(
    ofType(FETCH_JOKES),
    switchMap(() =>
      getJokes().pipe(
        map(response => jokesReceived(response)),
        catchError((err, act) => of(jokesFetchFailed(err))),
        takeUntil(action$.pipe(ofType(FETCH_JOKES_CANCELLED)))
      )
    ),
  );
};

export default fetchJokesEpic;

每当 FETCH_JOKES ajax 呼叫和成功调度 jokesReceived 行动或失败 jokesFetchFailed .

我想循环它,所以除非取消端点将再次调用后,上一次调用将完成(成功或失败)。

我想我可以用另一个史诗塔特将作出反应 JOKES_RECEIVED FETCH_JOKES_ERROR 行动和调度 取来你的笑话

import { ofType } from 'redux-observable';
import {
  delay,
  map,
} from 'rxjs/operators';
import {
  JOKES_RECEIVED,
  FETCH_JOKES_CANCELLED,
  FETCH_JOKES_ERROR,
  fetchJokes,
} from '../actions/jokes-action';

const pollJokes = (action$, state$) => {
  return action$.pipe(
    ofType(JOKES_RECEIVED, FETCH_JOKES_ERROR, FETCH_JOKES_CANCELLED),
    delay(2000),
    map(action => {
      console.log('pollJokes.map', action);
      if(action.type === FETCH_JOKES_CANCELLED)
      { 
        console.log("Cancelled")
        return { type: 'POLL_STOPPED' };
      }
      else {
        // loop
        return fetchJokes();
      }
    })
  );
};
export default pollJokes;

然而,这不工作时,我派遣 FETCH_JOKES_CANCELLED 行动。操作堆栈如下所示:

@INIT
FETCH_JOKES
JOKES_RECEIVED
FETCH_JOKES
JOKES_RECEIVED
...
FETCH_JOKES_CANCELLED
FETCH_JOKES
JOKES_RECEIVED
POLL_STOPPED
FETCH_JOKES
JOKES_RECEIVED
...

takeUntil 到 pollJokes 史诗般的,但同样糟糕的结果

const pollJokes = (action$, state$) => {
  return action$.pipe(
    ofType(JOKES_RECEIVED, FETCH_JOKES_ERROR, FETCH_JOKES_CANCELLED),
    delay(2000),
    map(action => {
      console.log('pollJokes.map', action);
      if(action.type === FETCH_JOKES_CANCELLED)
      { 
        console.log("Cancelled")
        return { type: 'POLL_STOPPED' };
      }
      else {
        // loop
        return fetchJokes();
      }
    }),


    takeUntil(action$.pipe(ofType(FETCH_JOKES_CANCELLED)))


  );
};

波尔笑话 获取\u已取消\u takeUntil公司 .

fetchJokes 什么时候 你收到的笑话

1 回复 | 直到 6 年前

1

2

Anas 6 年前

你需要使用 repeat ,以重新启动您的史诗,一旦它被取消 takeUntil

const pollJokes = (action$, state$) => {
  return action$.pipe(
    ofType(JOKES_RECEIVED, FETCH_JOKES_ERROR, FETCH_JOKES_CANCELLED),
    delay(2000),
    map(action => {
      console.log('pollJokes.map', action);
      if(action.type === FETCH_JOKES_CANCELLED)
      { 
        console.log("Cancelled")
        return { type: 'POLL_STOPPED' };
      }
      else {
        // loop
        return fetchJokes();
      }
    }),


    takeUntil(action$.pipe(ofType(FETCH_JOKES_CANCELLED))),
    repeat()

  );
};