无法访问Angular2服务对象属性

时间:2016-11-17 19:22:20

标签: angular service

我按照Angular2文档为我的应用程序创建了一项服务,但我似乎无法访问前端的信息。

当我尝试使用插值访问模板中的firstVariablesecondVariable时,我得到[Object object]。我决定使用json管道从对象中获得一个很好的读取,这是有效的。但是,我无法弄清楚为什么我无法访问firstVariablesecondVariable。我收到的错误是cannot read property 'firstVariable' of undefined

这是我的代码:

moose.component.ts

import { Component, OnInit } from '@angular/core';

import { MooseService } from './moose.service';

import { MooseCode } from './moose.code';


@Component({
  selector: 'moose-selector',
  templateUrl: './moose.component.html',
  providers: [MooseService]
})

export class MooseComponent implements OnInit {

  currentThing: MooseCode[];

  getCode(): void {
    this._mooseService.getCodeSlowly()
    .then(currentThing => this.currentThing = currentThing);
  }

  ngOnInit() {
    this.getCode();
  }

  constructor(private _mooseService: MooseService) {}

}

moose.service.ts

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

import { MooseCode } from './moose.code';
import { MOCK_DATA } from './mock-data';

@Injectable()

export class MooseService {

  getCode(): Promise<MooseCode[]> {
    return Promise.resolve(MOCK_DATA);
  }

  getCodeSlowly(): Promise<MooseCode[]> {
    return new Promise<MooseCode[]>(resolve =>
      setTimeout(resolve, 2000)) // delay 2 seconds
      .then(() => this.getCode());
  }

}

moose.component.html

<pre>
{{ currentThing | json }}
</pre>

moose.code.ts

export class MooseCode {

  constructor(
    public firstVariable: any,
    public secondVariable: any,
  ) {}
}

mock.data.ts

import { MooseCode } from './moose.code';

export const MOCK_DATA: MooseCode[] = [
  {
      'firstVariable': 'any',
      'secondVariable': 'any',
}
];

我尝试使用以下方法访问模板中的firstVariablesecondVariable

{{currentThing.firstVariable}}{{currentThing[0].firstVariable}}

什么都行不通!我做错了什么?

2 个答案:

答案 0 :(得分:0)

您的服务“getHomePageCodeSlowly无法解析。尝试:

setTimeout(resolve(MOCK_DATA), 2000))

然后@ component getCode() currentThing [0] .firstVariable或secondvariable

答案 1 :(得分:0)

@estus方法可行 - {{currentThing?[0].firstVariable}}。但是,如果您不想每次都使用问号,请使用ngIf - 这将以相同的方式工作。例如,假设:

ItemObject = {
  id: 1,
  name: "something",
  anotherProperty: "whatever",
  isThisReal: false
}
<div class="item" *ngIf="ItemsObject">
  <h1>{{ItemObject.isThisReal}}</h1>
</div>

输出应为:<h1>false</h1>