Redux-saga中间件

Redux-saga中间件

安装

npm install redux-saga --save
或
yarn add redux-saga

---

使用

1. 创建、使用、运行Redux-saga中间件

src/store/index.js

import { createStore, applyMiddleware, compose } from 'redux';
import thunk from 'redux-thunk';
import createSagaMiddleware from 'redux-saga';
import reducer from './reducer';
import sagas from './sagas'; // 创建sagas.js

// window.__REDUX_DEVTOOLS_EXTENSION__  可使用Redux DevTools插件
const composeEnhancers = window.__REDUX_DEVTOOLS_EXTENSION_COMPOSE__ ? window.__REDUX_DEVTOOLS_EXTENSION_COMPOSE__({}) : compose;

// 创建Redux-saga中间件
const sagaMiddleware = createSagaMiddleware();

// 使用Redux-thunk中间件、Redux-saga中间件
const enhancer = composeEnhancers(applyMiddleware(thunk, sagaMiddleware));

// 创建store
const store = createStore(reducer, enhancer);

// 运行saga中间件
sagaMiddleware.run(sagas);

export default store;

2. 创建sagas.js

src/store/sagas.js

import { put, takeEvery } from 'redux-saga/effects';
import axios from 'axios';
import { initListAction } from './actionCreator';

// generator 函数
function* mySaga() {
    // 接收 store.dispatch() 传过来的action
    // 接收到get_init_list的action后，会调用getInitList方法
    // getInitList可以执行异步操作
    yield takeEvery('get_init_list', getInitList);
}

function* getInitList() {
    try {
        let list = [];
        const res = yield axios.get('https://www.fastmock.site/mock/0764b93cba70add273910b232c51aad8/development/api/getHotList'); // 等待axios请求结束后，直接将结果赋值给res
        if (res.data.data.length > 0) {
            for (const val of res.data.data) {
                list.push(val.name);
            }
        }
        const action = initListAction(list);
        yield put(action); // 类似于store.dispatch(action);
    } catch (error) {
        console.log(error);
    }
}

export default mySaga;

3. action的统一管理

src/store/actionCreator.js

export const initListAction = list => ({
    type: 'init_list',
    list,
});

4. Reducer

src/store/reducer.js

const defaultState = {
    list: [],
};

export default (state = defaultState, action) => {
    let newState = JSON.parse(JSON.stringify(state)); // 深拷贝,不能直接修改state里的数据
    if (action.type === 'init_list') {
        newState.list = action.list;
    }
    return newState;
};

5. List.js

import { Component, Fragment } from 'react'; // 占位符
import store from './store/index';
import { List } from 'antd';
import 'antd/dist/antd.css';

class NewTodoList extends Component {
    constructor(props) {
        super(props);
        this.state = store.getState();
        store.subscribe(this.storeChange.bind(this)); // store发生改变时，自动触发
    }
    render() {
        return (
            <Fragment>
                <List bordered dataSource={this.state.list} renderItem={(item, index) => <List.Item> {item} </List.Item>} />
            </Fragment>
        );
    }
    componentDidMount() {
        const action = {
            type: 'get_init_list',
        };
        store.dispatch(action); // action不仅会被reducer接收，还会被redux-saga接收
    }
    storeChange() {
        this.setState(store.getState());
    }
}

export default NewTodoList;