angular4 怎么在子组件上双向绑定

Question

我是看到别人的代码实现双向绑定，但是我不知道怎么在子组件上接收这个值，求帮助，代码如下：

<h1>test</h1>
<div>
  <label for="username">heheda:</label>
  <input type="text" [(ngModel)]="username">
</div>
<app-test [(ngModel)]="username" ></app-test>

test.component.html

<div>
  <h2>test area</h2>
  <div>
    <label for="test"></label>
    <input type="text" [(ngModel)]='name'>
  </div>
</div>

test.component.ts

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

@Component({
  selector: 'app-test',
  templateUrl: './test.component.html',
  styleUrls: ['./test.component.css']
})
export class TestComponent implements OnInit {
  @Input('name') name = 'testName';
  constructor() { }

  ngOnInit() {
  }

}

Answer 1

实现 ControlValueAccessor 见 rating component