我有一个Firebase数据库,其顶部有一个users
节点。例如,我想获取该节点的第一个孩子。我正在尝试以这种方式访问,但是我说:
TypeError: "this.users[0] is undefined"
export class FirebaseService {
user: Observable<User | null>
userCollection: AngularFirestoreCollection<User>;
users: Observable<User[]>;
getUserByEmail(email) {
this.userCollection = this.afs.collection('users');
this.users = this.userCollection.valueChanges();
let a = this.users[0].name;
我已经看过很多教程,但是找不到出现错误的原因
答案 0 :(得分:3)
需要订阅valueChanges
this.userCollection.valueChanges().subscribe((item) => {
this.users = item;
console.log(this.users[0].name)
})