[英]React hooks and context api localstorage on refresh
在我的 SPA 中,我使用了反应钩子和上下文 API。 我需要持久化使用上下文 API 渲染的组件视图的当前 state 以便我可以通过应用程序实现全局组件条件渲染。
我在单个仪表板页面上有两个视图:概述和详细信息。 该按钮触发全局 state 更改,即使在页面刷新时,视图也应固定在 state 值上。
这是我的代码片段:
应用路由文件
import React, { useState } from "react";
import { Router, Route, Switch } from "react-router-dom";
import history from "../utils/history";
import { PyramidProvider } from "../context/pyramidContext";
import Dashboard from "../pages/dashboard/Dashboard";
const AppRoutes = () => {
return (
<div>
<React.Suspense fallback={<span>Loading...</span>}>
<Router history={history}>
<Switch>
<PyramidProvider>
<Route path="/" component={Dashboard} />
</PyramidProvider>
</Switch>
</Router>
</React.Suspense>
</div>
);
};
export default AppRoutes;
仪表板页面
import React, { useState, useEffect, useContext } from "react";
import { PyramidContext } from "../../context/pyramidContext";
import PyramidDetail from "../../components/pyramidUI/pyramidDetail";
import PyramidOverview from "../../components/pyramidUI/pyramidOverview";
const Dashboard = (props) => {
const { info, setInfo } = useContext(PyramidContext);
return (
<React.Fragment>
{info.uiname === "overview" ? <PyramidOverview /> : <PyramidDetail />}
</React.Fragment>
);
};
export default Dashboard;
概览组件
import React, { useState, useContext } from "react";
import { PyramidContext } from "../../context/pyramidContext";
const Overview = (props) => {
const { info, setInfo } = useContext(PyramidContext);
return (
<div className="d-flex flex-column dashboard_wrap">
<main>
<div className="d-flex">
<button
onClick={() => setInfo({ uiname: "detail", pyramidvalue: 1 })}
>
change view
</button>
</div>
</main>
</div>
);
};
export default Overview;
细节组件
import React, { useContext } from "react";
import { PyramidContext } from "../../context/pyramidContext";
// import axios from "axios";
const Detail = (props) => {
const { info, setInfo } = useContext(PyramidContext);
return (
<div className="d-flex flex-column dashboard_wrap">
<h2>Detail View</h2>
<div>
<button
type="button"
onClick={() => setInfo({ uiname: "overview", pyramidvalue: 0 })}
>
Back
</button>
</div>
</div>
);
};
export default Detail;
上下文文件
import React, { createContext, useEffect, useReducer } from "react";
let reducer = (info, newInfo) => {
return { ...info, ...newInfo };
};
const initialState = {
uiname: "overview",
pyramidvalue: 0,
};
const localState = JSON.parse(localStorage.getItem("pyramidcontent"));
const PyramidContext = createContext();
function PyramidProvider(props) {
const [info, setInfo] = useReducer(reducer, initialState || localState);
useEffect(() => {
localStorage.setItem("pyramidcontent", JSON.stringify(info));
}, [info]);
return (
<PyramidContext.Provider
value={{
info,
setInfo,
}}
>
{props.children}
</PyramidContext.Provider>
);
}
export { PyramidContext, PyramidProvider };
我单击按钮以呈现detail
视图,一旦刷新页面,组件就会将其视图更改为overview
而不是坚持detail
。 我检查了本地存储值,它正在正确更新,但组件视图仍然没有按照值保留。
我无法理解我在哪里做错了,请帮助解决这个问题? 提前致谢。
您永远不会在您的信息 state 中使用 localStage 的值,您应该将代码替换为:
const [info, setInfo] = useReducer(reducer, localState || initialState);
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