React redux api polling every x seconds

问题

I've got this working but i'm after a more 'best practice way'.

its using the https://icanhazdadjoke api to display a random joke that gets updated every x seconds. is there a better way of doing this?

eventually i want to add stop, start, reset functionality and feel this way might not be the best.

Any middleware i can use?

Redux actions

// action types
import axios from 'axios';
export const FETCH_JOKE = 'FETCH_JOKE';
export const FETCH_JOKE_SUCCESS = 'FETCH_JOKE_SUCCESS';
export const FETCH_JOKE_FAILURE = 'FETCH_JOKE_FAILURE';


function fetchJoke() {
  return {
    type: FETCH_JOKE
  };
}

function fetchJokeSuccess(data) {
  return {
    type: FETCH_JOKE_SUCCESS,
    data
  };
}

function fetchJokeFail(error) {
  return {
    type: FETCH_JOKE_FAILURE,
    error
  };
}

export function fetchJokeCall(){
  return function(dispatch){
    dispatch(fetchJoke());
    return axios.get('https://icanhazdadjoke.com', { headers: { 'Accept': 'application/json' }})
    .then(function(result){
      dispatch(fetchJokeSuccess(result.data))
    })
    .catch(error => dispatch(fetchJokeFail(error)));
  }
}

Redux reducer

import {combineReducers} from 'redux';
import {FETCH_JOKE, FETCH_JOKE_SUCCESS, FETCH_JOKE_FAILURE} from '../actions';

const defaultStateList = {
  isFetching: false,
  items:[],
  error:{}
};

const joke = (state = defaultStateList, action) => {
  switch (action.type){
  case FETCH_JOKE:
    return {...state, isFetching:true};
  case FETCH_JOKE_SUCCESS:
    return {...state, isFetching:false, items:action.data};
  case FETCH_JOKE_FAILURE:
    return {...state, isFetching:false, error:action.data};
  default:
    return state;
  }
};

const rootReducer = combineReducers({
  joke
});

export default rootReducer;

Joke component

import React, { Component } from 'react';
import { connect } from 'react-redux';
import PropTypes from 'prop-types';
import { fetchJokeCall } from '../actions';


class Joke extends Component {
  componentDidMount() {
    this.timer = setInterval(()=>  this.props.fetchJokeCall(), 1000);
  }
  componentWillUnmount() {
    clearInterval(this.timer)
    this.timer = null;
  }
  render() {
    return (
      <div>
        {this.props.joke.joke}
      </div>
    );
  }
}

Joke.propTypes = {
  fetchJokeCall: PropTypes.func,
  joke: PropTypes.array.isRequired
};

function mapStateToProps(state) {
  return {
    joke: state.joke.items,
    isfetching: state.joke.isFetching
  };
}

export default connect(mapStateToProps, { fetchJokeCall })(Joke);

回答1:

Redux-Sagas is better and we are using it in our applications as well, this is how you can poll using Redux-Sagas

Just to give you an idea this is how you can do it, You also need to understand how Redux-Sagas work

Action

export const FETCH_JOKE = 'FETCH_JOKE';
export const FETCH_JOKE_SUCCESS = 'FETCH_JOKE_SUCCESS';
export const FETCH_JOKE_FAILURE = 'FETCH_JOKE_FAILURE';
export const START_POLLING = 'START_POLLING';
export const STOP_POLLING = 'STOP_POLLING';

function startPolling() {
      return {
        type: START_POLLING
      };
    }

function stopPolling() {
      return {
        type: STOP_POLLING
      };
    }

function fetchJoke() {
  return {
    type: FETCH_JOKE
  };
}

function fetchJokeSuccess(data) {
  return {
    type: FETCH_JOKE_SUCCESS,
    data
  };
}

function fetchJokeFail(error) {
  return {
    type: FETCH_JOKE_FAILURE,
    error
  };
}

Reducer

import {combineReducers} from 'redux';
import {FETCH_JOKE, FETCH_JOKE_SUCCESS, FETCH_JOKE_FAILURE, START_POLLING, STOP_POLLING } from '../actions';

const defaultStateList = {
  isFetching: false,
  items:[],
  error:{},
  isPolling: false,
};

const joke = (state = defaultStateList, action) => {
  switch (action.type){
  case FETCH_JOKE:
    return {...state, isFetching:true};
  case FETCH_JOKE_SUCCESS:
    return {...state, isFetching:false, items:action.data};
  case FETCH_JOKE_FAILURE:
    return {...state, isFetching:false, error:action.data};
  case START_POLLING:
    return {...state, isPolling: true};
  case STOP_POLLING:
    return {...state, isPolling: false};
  default:
    return state;
  }
};

const rootReducer = combineReducers({
  joke
});

export default rootReducer;

Sagas

import { call, put, takeEvery, takeLatest, take, race } from 'redux-saga/effects'

import {FETCH_JOKE, FETCH_JOKE_SUCCESS, FETCH_JOKE_FAILURE, START_POLLING, STOP_POLLING } from '../actions';

import axios from 'axios';



function delay(duration) {
  const promise = new Promise(resolve => {
    setTimeout(() => resolve(true), duration)
  })
  return promise
}

function* fetchJokes(action) {
  while (true) {
    try {
      const { data } = yield call(() => axios({ url: ENDPOINT }))
      yield put({ type: FETCH_JOKE_SUCCESS, data: data })
      yield call(delay, 5000)
    } catch (e) {
      yield put({ type: FETCH_JOKE_FAILURE, message: e.message })
    }
  }
}

function* watchPollJokesSaga() {
  while (true) {
    const data = yield take(START_POLLING)
    yield race([call(fetchJokes, data), take(STOP_POLLING)])
  }
}

export default function* root() {
  yield [watchPollJokesSaga()]
}

You can also use Redux-Observable, if you want to get more into this read this article

回答2:

redux-saga is great and I've been using this with redux. It provides a great api to do things like delay, polling, throttling, race conditions, task cancellations. So using redux-saga, you can add a watcher whcih will keep on pooling

function* pollSagaWorker(action) {
  while (true) {
    try {
      const { data } = yield call(() => axios({ url: ENDPOINT }));
      yield put(getDataSuccessAction(data));
      yield call(delay, 4000);
    } catch (err) {
      yield put(getDataFailureAction(err));
    }
  }
}

回答3:

I've been working on pretty much the same problem, except that I wasn't concerned about starting and stopping the poll. For some reason the while loop kept freezing my app so I dispensed of it and instead set up my saga like this.

import { all, takeLatest, call, put } from 'redux-saga/effects';
import axios from 'axios';

import { API_CALL_REQUEST, API_CALL_SUCCESS, API_CALL_FAILURE, API_CALL_FETCHED } from 
'../actions/giphy';

function apiFetch() {
  let randomWord = require('random-words');
  let API_ENDPOINT = `https://api.giphy.com/v1/gifs/search? 
                   api_key=MYKEY&q=${randomWord()}&limit=12`;
  return axios({
    method: "get",
    url: API_ENDPOINT
 });
}

export function* fetchImages() {
  try {
   const res = yield call(apiFetch)
   const images = yield res.data
   yield put({type: API_CALL_SUCCESS, images})

} catch (e) {
  yield put({type: API_CALL_FAILURE, e})
  console.log('Error fetching giphy data')
 }
}

export default function* giphySaga() {
  yield all([
    takeLatest(API_CALL_REQUEST, fetchImages),
 ]);
}

Then inside my component I added this.

 componentDidMount() {
   this.interval = setInterval(() => {
   this.props.dispatch({type: 'API_CALL_REQUEST'});
   }, 5000);
  }

componentWillUnmount() {
  clearInterval(this.interval)
}

It's working, but would like some feedback on how this could be possibly improved.

来源：https://stackoverflow.com/questions/52413362/react-redux-api-polling-every-x-seconds

标签

reactjs

redux

polling