javascript – 带范围的Angular2指令

Angular2中的指令没有“范围”,而组件则没有.但就我而言,我需要Directive来创建一个范围.看看我的App组件 – 它有一个HTML模板,并且在foo指令可能出现的任何元素上都是ANYWHERE.这应该从服务中获取一些日期并将其分配给元素.

在Angular1中它很容易……指令可以有自己的范围.但在Angular 2中,我找不到任何(甚至是肮脏的)方法来实现这一点.

它看起来像一个简单的任务,不是吗？

@Directive({
  selector: '[foo]'
})
class FooDirective {
  @Input()
  public id:string;

  public bar;

  constructor() {
     this.bar = 'This is the "bar" I actually need. It is taken from DB let's say..' + this.id;
  }
}




@Component({
  selector: 'app',
  template: `
     <div foo id="2">
       This is random content 1: {{bar}}
     </div>

     <div foo id="2">
       This is random content 2: {{bar}}
     </div>
  `,
  directives: [FooDirective]
})
class App {
  bar:string = 'This should be ignored, I need "bar" to be set from directive!';
}

bootstrap(App);

解决方法:

你可以尝试使用一个引用应用指令的局部变量：

@Component({
  selector: 'app'
  template: `
    <div foo id="2" #dir1="foo">
      This is random content 1: {{dir1.bar}}
    </div>

    <div foo id="2" #dir2="foo">
      This is random content 2: {{dir2.bar}}
    </div>
  `,
  directives: [FooDirective]
})
class App {
  bar:string = 'This should be ignored, I need "bar" to be set from directive!';
}

在您的情况下,使用当前组件(App one)的属性评估栏.

编辑(关注@ yurzui的评论)

您需要在指令中添加exportAs属性：

@Directive({
  selector: '[foo]',
  exportAs: 'foo'
})
class FooDirective {
  (...)
}

标签：javascript,angular,angular2-directives
来源： https://codeday.me/bug/20190829/1758306.html