使用angular2检查数据是否从firebase传回

import { AngularFireDatabase } from '@angular/fire/database';

@Component({
  // 组件配置
})
export class MyComponent {
  users: any;

  constructor(private db: AngularFireDatabase) {
    this.users = db.object('users').valueChanges();
  }
}

import { AngularFireDatabase } from '@angular/fire/database';

@Component({
  // 组件配置
})
export class MyComponent implements OnInit {
  users: any;

  constructor(private db: AngularFireDatabase) {}

  ngOnInit() {
    this.users = this.db.object('users').valueChanges();
    this.users.subscribe(data => {
      console.log(data); // 在控制台打印数据
      // 在这里可以进行数据的检查和处理
    });
  }
}