Question

创建上下文

export default React.createContext({
user:null,
login:()=>{}
})

上下文控制器

export default class ContextHandler extends Component{
state = {
    user: null,
}
logout = () => {
    this.setState({
        user: null
    })
}

login = user => {
    this.setState({
        user: user
    })
};

render(){
    return(
        <AuthContext.Provider value={{ user: this.state, login: this.login, logout: this.logout }} >
            {this.props.children}
        </AuthContext.Provider>
    )
}
}

App.js

class App extends Component{
render() {
    return (
            <BrowserRouter>
                <div>
                    <Switch>
                        <Route path="/" exact component={Header} />
                        <Route path="/login" exact component={Login} />
                        <Route path="/profile" exact component={UserProfile} />
                        <Route path="/inputform" exact component={InputForm} />
                    </Switch>
                </div>
            </BrowserRouter>
    )
}
}

export default App;

index.js

ReactDOM.render((
<ContextHandler>
    <App/>
</ContextHandler>
),
document.getElementById('root'));
registerServiceWorker();

用户个人资料页

componentDidMount() {
    if (!this.context.user) {
        return ( <Redirect to = "/login"/> )
    }

    else{
        this.setState({
            loading:true
        })
        getUserEntries(this.context.user.token,(entries)=>{
            if(entries !== null){
                this.setState({
                    userEntries:entries
                })
            }
        })
    }
}

   render() {
    let samples, producers
    if(!this.context.user){
        return(
            <Redirect to="/login"/>
        )
    }

    if (this.state.userEntries) {
        samples = (this.buildList(this.state.userEntries.samples))
        producers = (this.buildList(this.state.userEntries.producers))
    }

登录后，我将被定向到具有正确上下文的用户页面。一旦导航到另一个页面并尝试返回到用户配置文件页面，上下文就会丢失。而且我必须再次登录？

使用上下文的仅有的两个组件是导航栏和用户个人资料页面。注意：我使用的是新的16.6上下文API，即渲染器中没有消费者标签。

重定向后反应上下文丢失

0 个答案: