如何获取对象的属性？

Question

我从服务器获取json

 getTextContent() {
   this._main.getVar()
   .subscribe(
     text_content => this.text_content = text_content,
     error => console.error('Error: ' + this.errorMessage),
     () => console.log('Completed!',this.text_content));
}

在控制台和屏幕上我看到了

那很好。但是当我尝试在屏幕上显示{{text_content.category_content.home}}时，我收到错误TypeError: Cannot read property 'category_content' of undefined in [{{text_content.category_content.home}} in HomeComponent@1:3] 我应该使用dot来获取对象的属性还是其他任何东西？

更新

import {Component,OnInit} from 'angular2/core';
import {CORE_DIRECTIVES} from 'angular2/common';
import {MainService} from '../../shared/services/main.service';
import {Http} from 'angular2/http';
import {Title} from 'angular2/platform/browser';

 @Component({
   selector: 'sd-home',
   moduleId: module.id,
   viewProviders: [MainService],
   templateUrl: './home.component.html',
   styleUrls: ['./home.component.css'],
   directives: [CORE_DIRECTIVES]
 })
export class HomeComponent implements OnInit {
  public http:Http;
  public pageTitle : String;
  private text_content : Object;
  private errorMessage : String;
 constructor (private _title:Title, private _main:MainService) {
  }
 ngOnInit() {
    this.getTextContent();
    console.log('text',this.text_content.category_content);
   }

 getTextContent() {
   this._main.getVar()
   .subscribe(
     text_content => this.text_content = text_content,
     error => console.error('Error: ' + this.errorMessage),
     () => console.log('Completed!',this.text_content));
    }
    }

属性'category_content'在'Object'

类型上不存在

Answer 1

您需要将text_content放入$scope。因此，在您的成功案例结束时，您需要$scope.text_content = this.text_content。这将使消化器可以使用它并且它将被正确渲染。

Answer 2

可能是angular2 zone问题，

import {NgZone} from 'angular2/core';
 constructor (private _title:Title, private _main:MainService,private zone:NgZone) {
  }
getTextContent() {
    this.zone.run(()=>
    this._main.getVar()
              .subscribe(
                text_content => this.text_content = text_content,
                error => console.error('Error: ' + this.errorMessage),
                () => console.log('Completed!',this.text_content));

              );
}

试试这个。

Answer 3

使用

{{text_content?.category_content?.home}}

当Angular第一次尝试解析绑定时，

text_content尚未可用，因为数据处理为异步。