小编Vin*_*eda的帖子

我真的不知道该如何解决。如何解决此错误？

in user.service.ts:
import { Injectable } from '@angular/core';

import { AngularFireDatabase, AngularFireList, AngularFireObject } from 'angularfire2/database';

import {AppUser} from './models/app.user';
import * as firebase from 'firebase';
import { Observable } from 'rxjs';

@Injectable({
  providedIn: 'root'
})
export class UserService {


  constructor(private db: AngularFireDatabase) { }

  save(user: firebase.User) {
    this.db.object('/users/' + user.uid).update({
      name: user.displayName,
      email: user.email
    });
  }

  get(uid: string): AngularFireObject<AppUser> {
    return this.db.object('/users/' + uid);
  }



in admin-auth-guard.service:

import { Injectable } from '@angular/core';
import { Observable } from …