Day 25 - redux-saga 文件范例

Q_Q 没学完啦

Redux-saga 范例

import { createStore, applyMiddleware } from 'redux'
import createSagaMiddleware from 'redux-saga'

import reducer from './reducers'
import mySaga from './sagas'

// create the saga middleware
const sagaMiddleware = createSagaMiddleware()
// mount it on the Store
const store = createStore(
  reducer,
  applyMiddleware(sagaMiddleware)
)

// then run the saga
sagaMiddleware.run(mySaga)

// render the application

sagas.js

import { call, put, takeEvery, takeLatest } from 'redux-saga/effects'
import Api from '...'

// 工作的 Saga：当 action 是 USER_FETCH_REQUESTED 时被触发
function* fetchUser(action) {
   try {
      const user = yield call(Api.fetchUser, action.payload.userId);
      yield put({type: "USER_FETCH_SUCCEEDED", user: user});
   } catch (e) {
      yield put({type: "USER_FETCH_FAILED", message: e.message});
   }
}

/*
  在每次 dispatch `USER_FETCH_REQUESTED` action 时，启动 fetchUser。
  允许同时取得使用者。
*/
function* mySaga() {
  yield takeEvery("USER_FETCH_REQUESTED", fetchUser);
}

/*
  另外你也可以使用 takeLatest。

  但不允许同时取得使用者。当一个 fetch 已经在 pending 时，如果取得 dispatch「USER_FETCH_REQUESTED」，
  正在等待的 fetch 会被取消，只执行最新的发出的 USER_FETCH_REQUESTED。
*/
function* mySaga() {
  yield takeLatest("USER_FETCH_REQUESTED", fetchUser);
}

export default mySaga;