firebase.auth().onAuthStateChanged((user) => { if(user) { this.isLoggedIn = true; //Set user loggedIn is true; this.isAdmin = false; firebase.database().ref('/userProfile/' + user.uid).once('value').then(function(snapshot) { let userInfo = snapshot.val(); if(userInfo.isAdmin == true) { //ERROR AT THIS LINE: //Error: Uncaught (in promise): TypeError: Cannot set property 'isAdmin' of null this.isAdmin = true; console.log(userInfo); } }); } else { this.isLoggedIn = false; //Set user loggedIn is false; } });
我在第8行遇到错误
Error: Uncaught (in promise): TypeError: Cannot set property ‘isAdmin’ of null
请帮忙!
要么你可以使用箭头功能
firebase.database().ref('/userProfile/' + user.uid).once('value') .then((snapshot) => {
或使用
var self = this; firebase.database().ref('/userProfile/' + user.uid).once('value') .then(function(snapshot) { self.isAdmin = true;
另见https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Functions/Arrow_functions