如何在 ngOnInit() 方法中显示来自 Http get 请求的对象？

Question

我在显示对象的属性时遇到问题，该对象是通过 Angular 中的 Http get 请求接收到的。我正在尝试在 ngOnInit() 方法中调用 HTTP 请求，这似乎工作正常：我收到了我需要的对象。但是后来我无法在 http 文件中显示它（属性未定义）。看来我无法将 observable 连接到对象属性。我做错了什么？

组件：

import { Component, OnInit } from '@angular/core';
import {Package} from "../shared/package";
import { Http} from "@angular/http";
import 'rxjs/Rx';

@Component({
  selector: 'app-basket',
  templateUrl: './basket.component.html',
  styleUrls: ['./basket.component.css']
})
export class BasketComponent implements OnInit {

package: Package;
  private baseUrl: string = 'https://basket-211b4.firebaseio.com/.json';

  constructor(private http: Http) { }

  ngOnInit() {
    this.http.get(`${this.baseUrl}`).subscribe(
      (result) =>{
      this.package = result.json();
        console.log(this.package);
      }
    )
  }

Http 文件：

 <li class="row totals">
        <span class="price" >{{ package.id }}</span>
      </li>

包裹class：

import {User} from "./user";
import {Service} from "./service";
export class Package {
  constructor(public id: number, public totalCost: number, public dateCreated: string, public user: User,
              public services: Service[]){}
}

控制台错误：./BasketComponent class BasketComponent 中的错误 - 内联 template:31:29 原因：无法读取未定义的属性 'id'

控制台显示的对象：Object {dateCreated: "2017-05-14T18:47:56.000+0000", id: 1, services: Array(3), totalCost: 3600, user: Object}

Answer 1

您可以使用安全导航 (?) 运算符来显示属性，

<li class="row totals">
    <span class="price" >{{ package?.id }}</span>
</li>

如何在 ngOnInit() 方法中显示来自 Http get 请求的对象？

How to display an object from Http get request in ngOnInit() method?

angular

angular2-http