通过本地存储注销功能

Question

所以这里我通过本地存储令牌实现了登录功能。我在开发工具/应用程序中创建用户时得到了令牌，它将我重定向到正在工作的主页。不起作用的是这个。创建一个用户，它正在工作，但当它加载时，它应该显示登出而不是登录，并且应该隐藏cart组件。我在哪里犯错误上下文Api

import React from "react";
const UserContext = React.createContext();
function getUserFromLocalStorage() {
return localStorage.getItem("authToken")
? JSON.parse(localStorage.getItem("authToken"))
: { username: null, token: null };
}
function UserProvider({ children }) {
const [user, setUser] = React.useState(getUserFromLocalStorage());

const history = useHistory();
const logoutHandler = () =>{
localStorage.removeItem("user");
history.push("/")
}
return (
<UserContext.Provider
value={{ user, logoutHandler  }}
>
{children}
</UserContext.Provider>
);
}
export { UserContext, UserProvider };

登录链接

import React from "react";
import { Link } from "react-router-dom";
import { UserContext } from "../../context/user";
import { useHistory } from "react-router-dom"
export default function LoginLink() {
const { user, logoutHandler } = React.useContext(UserContext);
if (user.authToken) {
return (
<button
onClick={() => {
logoutHandler();
}}
className="login-btn"
>
logout
</button>
);
}
return <Link to="/login">login</Link>;
}

标题

import React from 'react';
import { Link, useHistory } from "react-router-dom";
import Search from './Search';
import './Header.css'
import SearchBooks from './SearchBooks';
import LoginLink from '../Signin/LoginLink';
import CartLink from '../Cart/CartLink';
import { UserContext } from '../../context/user';
const Header = () => {
const { user } = React.useContext(UserContext);
return (
<div className='header__container'>
<Link to='/'>
<img src='/audi.png' />
</Link>  
<li>
<LoginLink />
</li>
{user.authToken &&(
<CartLink /> 
)    
}      
</div>
)
}
export default Header

登录组件

import { useState, } from "react";
import { useHistory } from "react-router-dom"
import axios from "axios";
import { Link } from "react-router-dom";
import "./Signin.css";
const Login = () => {
const { user, setUser } = React.useContext(UserContext);
const [email, setEmail] = useState("");
const [password, setPassword] = useState("");
const [error, setError] = useState("");
const history = useHistory()

const loginHandler = async (e) => {
e.preventDefault();
const config = {
header: {
"Content-Type": "application/json",
},
};
try {
const { data } = await axios.post(
"http://localhost:5000/api/auth/login",
{ email, password },
config
);
localStorage.setItem("authToken", data.token);
setUser(user)
history.push("/");
} catch (error) {
if (error.response) {
setError(error.response.data.error);
}
setTimeout(() => {
setError("");
}, 5000);
}
};
return (
<div className="login-screen">
<form onSubmit={loginHandler} className="login-screen__form">
<h3 className="login-screen__title">Login</h3>
{error && <span className="error-message">{error}</span>}
<div className="form-group">
<label htmlFor="email">Email:</label>
<input
type="email"
required
id="email"
placeholder="Email address"
onChange={(e) => setEmail(e.target.value)}
value={email}
tabIndex={1}
/>
</div>
<div className="form-group">
<label htmlFor="password">
Password:{" "}
<Link to="/forgotpassword" className="login-screen__forgotpassword">
Forgot Password?
</Link>
</label>
<input
type="password"
required
id="password"
autoComplete="true"
placeholder="Enter password"
onChange={(e) => setPassword(e.target.value)}
value={password}
tabIndex={2}
/>
</div>
<button type="submit" className="btn btn-primary">
Login
</button>
<span className="login-screen__subtext">
Don't have an account? <Link to="/register">Register</Link>
</span>
</form>
</div>
);
};
export default Login;

Answer 1

登录后，您只在localStorage中设置了authToken，而没有在Provider中设置。您需要在登录后调用setUser，以便Header组件知道用户已登录