我如何在React Native中正确使用Firebase的onAuthStateChanged?

问题描述

我对 firebase 函数 onAuthStateChanged()感到困惑.

componentDidMount() {
fbAuth.onAuthStateChanged(function(user) {
  if (user) { //THIS TRIGGERS BOTH AT LOGIN AND REGISTRATION
    console.log("LOGGED IN");
  } else {
    //TRIGGERS WHEN LOGGING OUT; NOT WHEN FAILING TO LOGIN!
    console.log("LOGGED OUT");
  }
});
}

我认为当用户登录时会触发if(user)块，但是在创建新帐户时也会触发console.log.如何设置仅在登录时触发(而不是通过创建新帐户触发)的条件?

I thought that the if(user) block triggered when the user has logged in, but the console.log is also triggered when a new account is created. How do I make a conditional that only triggers at login (and not by creating a new account?)

推荐答案

onAuthStateChanged(nextOrObserver, error, completed) returns function()

返回一个监听器功能

因此，当安装组件时，您需要监听；当卸载 <取消监听

Therefore you need to listen it when the component is mounted and unlisten when the component is unmounted

如果要专门监听登录，则需要制作一个单独的组件

You need to make a separate Component if you want to listen specifically for Login

Login.js //或您的任何登录组件都是

Login.js // Or whatever your login component is

componentDidMount() {
    // Bind the variable to the instance of the class.
    this.authFirebaseListener = firebase.auth().onAuthStateChanged((user) => {
      this.setState({
        loading: false,  // For the loader maybe
        user, // User Details
        isAuth: true
      });
    });

  }

componentWillUnmount() {
   this.authFirebaseListener && this.authFirebaseListener() // Unlisten it by calling it as a function
}

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