Redux数据持久化

背景

    在开发的过程中，数据用redux管理，觉得希望将数据持久化保存，也就是说当用户下一次打开APP或者网站的时候，我们希望浏览器或者APP自动加载上次的数据，怎么办？有没有一个统一的方式？

有的，这就是简单易用的redux-persist,事情会比你想象中的简单太多。

下面是官方示例代码：

  

import { PersistGate } from 'redux-persist/es/integration/react'
 
import configureStore from './store/configureStore'
 
const { persistor, store } = configureStore()
 
const onBeforeLift = () => {
  // take some action before the gate lifts
}
 
export default () => (
  <Provider store={store}>
    <PersistGate 
      loading={<Loading />}
      onBeforeLift={onBeforeLift}
      persistor={persistor}>
      <App />
    </PersistGate>
  </Provider>
)

首先你的结构应该是拥有reducers的，在我的代码中，我还加入了redux-thunk中间件，在 Redux 应用中实现异步性。

import React, { Component } from 'react';      
 import {AppRegistry} from 'react-native';      
 import { createStore ,applyMiddleware } from 'redux'
 import { Provider } from 'react-redux'     
 import App from "./src/App";       
 import reducers from './src/reducers/reducers' 
 import thunk from 'redux-thunk';       
 export default class CoinOnline extends Component {        
   render() {
     const store = createStore(App,applyMiddleware(thunk)); 
     return (
       <Provider store={store}>
        <App />
       </Provider>      
       );
     }
 }
AppRegistry.registerComponent('CoinOnline', () => CoinOnline);  

实现步骤

第一步，引入我们需要的方法

import {persistStore, persistCombineReducers} from 'redux-persist';
import { PersistGate } from 'redux-persist/es/integration/react';

第二步，重新封装reducer,用persistCombineReducers()方法加载配置和reducer。

const config = {
    key: 'root',
    storage,
};
let reducer = persistCombineReducers(config, reducers);

第三步，在redux的<Provider></Provider>内层嵌套<PersistGate></PersistGate>

<Provider store={store}>
                <PersistGate persistor={persistor}>
                    <App />
                </PersistGate>
</Provider>

 代码汇总

import React, { Component } from 'react';
import {
    AppRegistry,
} from 'react-native';
import { createStore ,applyMiddleware, compose } from 'redux'
import { Provider } from 'react-redux'
import App from "./src/App";
import reducers from './src/reducers/reducers'
import thunk from 'redux-thunk';
import {persistStore, persistCombineReducers} from 'redux-persist';
import { PersistGate } from 'redux-persist/es/integration/react';
 
import storage from 'redux-persist/es/storage' // default: localStorage if web, AsyncStorage if react-native
 
const config = {
    key: 'root',
    storage,
};
 
function configureStore(){
    let reducer = persistCombineReducers(config, reducers);
    let store = createStore(reducer, applyMiddleware(thunk));
    let persistor = persistStore(store);
    return { persistor, store }
}
export default class CoinOnline extends Component {
    render() {
        const { persistor, store } = configureStore();
        return (
            <Provider store={store}>
                <PersistGate persistor={persistor}>
                    <App />
                </PersistGate>
            </Provider>
 
        );
    }
}
AppRegistry.registerComponent('CoinOnline', () => CoinOnline);

Tips: 

如果createStore有需要加载多个参数，需要用compose将其拼装起来。

比如在测试的时候我还使用了remote-redux-devtools调试神器，代码如下，

let store = createStore(reducer, compose(applyMiddleware(thunk),devToolsEnhancer({ realtime: true, port: 8000 })));

每次启动之前reducer-persist都会默认先dispatch两个动作

PERSIT和REHYDRATE,会把上一次的redux中的states注入到当前组件中，即完成了持久化。

 

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