在Ionic App中链接Firebase身份验证和Firestore时onSnapshot TypeError

Question

我想使用Firebase身份验证uid作为Firestore（字符串）的集合名称，为在我的离子Web应用程序上注册的每个用户创建一个单独的集合。 当我这样做时，遇到以下错误：

错误：未捕获（承诺）：TypeError：无法读取未定义的属性'onSnapshot'

TypeError：无法读取未定义的属性“ onSnapshot”

而且该集合未在我的Firestore数据库中创建，如何解决此问题

离子代码

// firebase.service.ts
import { Injectable, OnInit } from "@angular/core";
import { AngularFirestore } from "@angular/fire/firestore";
import { AuthenticationService } from "./authentication.service";
import { NavController } from "@ionic/angular";

@Injectable({
  providedIn: "root",
})
export class FirebaseService {
  collectionName: string;

  constructor(
    private firestore: AngularFirestore,
    private authService: AuthenticationService,
    private navCtrl: NavController
  ) {}

  ionViewdidLoad() {
    
    this.authService.userDetails().subscribe((user) => {
      console.log(user.uid);
      this.collectionName = user.uid;
    });
  }

  ngOnInit() {}

  create_student(record) {
    return this.firestore.collection(this.collectionName).add(record);
  }

  read_students() {
    return this.firestore.collection(this.collectionName).snapshotChanges();
  }

  update_student(recordID, record) {
    this.firestore.doc(this.collectionName + "/" + recordID).update(record);
  }

  delete_student(record_id) {
    this.firestore.doc(this.collectionName + "/" + record_id).delete();
  }
}