reactjs – 在React.JS中刷新后如何让用户登录firebase？

安装组件时,我想呈现登录屏幕或应用程序,具体取决于用户登录的情况.但是,每次刷新时,用户都会注销.我如何让他们登录？

应用组件：

firebase.initializeApp(config); //init the firebase app...

class App extends Component {//this component renders when the page loads
constructor(props){
  super(props);

  this.state = {user: firebase.auth().currentUser};//current user
}
render(){
    if (this.state.user) {//if you are logged in
          return (
            <Application/>
          );
    } else {//if you are not logged in
          return (
            <Authentication/>
          );
    }
}

}

这是我用来登录用户的方法(工作正常)：

let email = "some";
let password = "thing";
const auth = firebase.auth();
const promise = auth.signInWithEmailAndPassword(email, password);

用户的令牌会自动持久保存到本地存储,并在加载页面时读取.这意味着重新加载页面时,应再次自动对用户进行身份验证.

最可能的问题是您的代码未检测到此身份验证,因为您的App构造函数在Firebase重新加载并验证用户凭据之前运行.要解决此问题,您需要listen for the (asynchronous) onAuthStateChanged() event,而不是同步获取值.

constructor(props){
  super(props);
  firebase.auth().onAuthStateChanged(function(user) {
    this.setState({ user: user });
  });
}