javascript - Angular 4 : Load data from Json

Question

我是 Angular 的新手。我正在做的是在点击时从 json 文件加载数据，到目前为止我已经正确地完成了。

但是我卡住的地方是在点击之前加载第一个json对象，即在页面加载时加载第一个对象

typescript

export class RequestComponent{
  people: Object[];
  constructor(http:Http){
    http.get('data.json').subscribe(res => {
      this.people = res.json();
    });
  }

  public currentStatus;
  public setThis = (people) => this.currentStatus = people;
}

HTML

  <ul class="col-md-4">
    <li *ngFor="let person of people" (click)="setThis(person)">
      <span><i class="fa fa-cog" aria-hidden="true"></i></span>
      <p>{{ person.name }}</p>
    </li>
  </ul>
   <div *ngIf="currentStatus" class="col-md-8 right-section">
      <h2>{{ currentStatus.name }}</h2>
      <img [src]="currentStatus.img" class="img-responsive"/>
   </div>

Answer 1

尝试在 ngOnInit() 函数中加载 json。

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

export class RequestComponent implements ngOnInit{
  people: Object[];

  constructor(private http:Http){}

  ngOnInit(){
      this.http.get('data.json').subscribe(res => {
      this.people = res.json();
    });
  }
}

并添加 ngIf 来显示您的记录，因此它不会在加载 people 之前尝试显示它。

<ul *ngIf="people" class="col-md-4">
    <li *ngFor="let person of people" (click)="setThis(person)">
        <span><i class="fa fa-cog" aria-hidden="true"></i></span>
        <p>{{ person.name }}</p>
    </li>
</ul>
<div *ngIf="currentStatus" class="col-md-8 right-section">
    <h2>{{ currentStatus.name }}</h2>
    <img [src]="currentStatus.img" class="img-responsive" />
</div>