Angular2 访问组件内的选择事件更改 [英] Angular2 access a select event change within the component

问题描述

使用 Angular2s 表单并尝试找出使用选择处理事件的过程.我有一个存储在选项中的对象 Heros.我想要做的是，当我英雄被选中时，触发一个事件到父组件，该事件将对结果做一些事情.但是，我找不到在选择更改时能够接收事件的具体示例(即列表中的新英雄被选中).

Working with Angular2s forms and trying to figure out the process of handling events with selects. I have an object Heros that is stored in the options. What I want to do is that when I hero is selected, trigger an event to the parent component that will do something with the results. However, I can't find a concrete example of being able to receive an event when the selection has changed (ie a new hero in the list as been selected).

interface Hero {
  id: number;
  name: string;
}
@Component({
  selector: 'my-app',
  template:`
  <h1>{{title}}</h1>
  <form>
    <select>
        <option *ngFor="#hero of heros "
                [value]="hero">
            {{hero .name}}
        </option>
    </select>
  </form>
`
})
   export class AppComponent {
   @Input() heros:Observable<Hero>
   @Output("selectedHeroChange") selectedHeroChange:EventEmitter<any> = new EventEmitter

   onHeroChange(hero:Hero){
      this.selectedHeroChange._next(hero);
   }    
}

提前致谢！

推荐答案

在选择更改时执行代码并使用 id 属性或 index 作为值`:

Execute code on select change and use an id property or index as value`:

<select (change)="onHeroChange($event)">
    <option *ngFor="#hero of heros; #i=index"
  [value]="hero.id">
      <!-- [value]="i" -->
        {{hero.name}}
    </option>
</select>

从事件中获取选定的值

onHeroChange(event:Event):void {
  Hero hero = heros.firstWhere(
      (Hero hero) => hero.id == (event.target as SelectElement).value);
  // Hero hero = heros[int.parse((event.target as SelectElement).value)];
  selectedHero = hero;
  selectedHeroChange.add(hero);
}

另见https://github.com/angular/angular/issues/4843#issuecomment-170147058

另见 在 Angular 2 中将选择元素绑定到对象

这篇关于Angular2 访问组件内的选择事件更改的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！