我正在创建一个应用程序,它使用 openweather API 获取用户输入的城市列表及其各自的天气。因此,我希望在刷新页面后保留这些城市。我知道如何使用浏览器 localStorage API 保存数据。但我不知道如何通过中间件保存它并将其传递给提供者。
下面是我的主要 Index.js 文件:
import React from 'react';
import ReactDOM from 'react-dom';
import { Provider } from 'react-redux';
import { createStore, applyMiddleware } from 'redux';
import ReduxPromise from 'redux-promise';
import App from './components/app';
import reducers from './reducers';
import {loadState,saveState} from './localStorage';
const persistedState=loadState();
const store=createStore(persistedState);
store.subscribe(()=>{
store.getState()
});
const createStoreWithMiddleware =
applyMiddleware(ReduxPromise)(createStore);
ReactDOM.render(
<Provider store={createStoreWithMiddleware(reducers)}>
<App />
</Provider>
, document.querySelector('.container-fluid'));
这是 localStorage.js 文件-:
export const loadState=()=>{
try{
const serializedState=localStorage.getItem('state');
if(serializedState===null){
return undefined;
}
return JSON.parse(serializedState);
}catch(err){
return undefined;
}
};
export const saveState=(state)=>{
try {
const serializedState=JSON.stringify(state);
localStorage.setItem('state',serializedState);
}catch(err){
console.log(err);
}};
我已将reducer写入reducers文件夹中的不同文件中。
reducers/index.js -:
import { combineReducers } from 'redux';
import WeatherReducer from './reducer_weather';
const rootReducer = combineReducers({
weather:WeatherReducer
});
export default rootReducer;
还有另一个 reducer reducer /reducer_weather.js -:
import {FETCH_WEATHER} from '../actions/index';
import {DELETECITY} from '../actions/deleterow';
export default function(state=[],action){
switch(action.type){
case FETCH_WEATHER:
console.log([action.payload.data, ...state]);
return [action.payload.data, ...state];
case DELETECITY:
console.log([...state].filter((weather)=>{
return weather.city.id!==action.payload
}));
return [...state].filter((weather)=>{
return weather.city.id!==action.payload
});
default:
return state;
};
}
在使用 localStorage 来保存应用程序状态之前,我的代码运行良好。但现在它向我显示一个错误。我面临关于 const createStoreWithMiddleware =
applyMiddleware(ReduxPromise)(createStore);
的问题
如何使用这个中间件来使用store以及如何传入<Provider>
标签的存储属性?
最佳答案
我建议您使用redux-persist .
Persist and rehydrate a redux store
使用此中间件,您在 Redux Store 中拥有的所有数据将自动保存到 localStorage (也可以使用不同类型的存储)。因此,当您刷新页面时,先前请求中已保留的数据将自动重新水化(推送)回 Store。
<小时/>示例,取自文档:
配置:
// configureStore.js
import { createStore } from 'redux'
import { persistStore, persistReducer } from 'redux-persist'
import storage from 'redux-persist/lib/storage' // defaults to localStorage for web and AsyncStorage for react-native
import rootReducer from './reducers'
const persistConfig = {
key: 'root',
storage,
}
const persistedReducer = persistReducer(persistConfig, rootReducer)
export default () => {
let store = createStore(persistedReducer)
let persistor = persistStore(store)
return { store, persistor }
}
用法:
import { PersistGate } from 'redux-persist/integration/react'
// ... normal setup, create store and persistor, import components etc.
const App = () => {
return (
<Provider store={store}>
<PersistGate loading={null} persistor={persistor}>
<RootComponent />
</PersistGate>
</Provider>
);
};
关于javascript - 如何使用中间件在 Redux 应用程序中编写 localStorage?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/53065359/