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
错误:未捕获(在承诺中):TypeError:无法设置属性' isAdmin'为null
答案 0 :(得分:10)
您可以使用箭头功能
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;
否则this
在被调用时不会指向当前函数。
另见https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Functions/Arrow_functions