Html 如何在angular 7中单击按钮时取消选中复选框

我有几个复选框，它们的值来自循环，这里我的要求是只有onload所有复选框默认情况下会被选中，但是单击clear按钮所有复选框都应该被取消选中，下面是代码

home.component.html 试着这样做：

.html

如果无法更改json，请执行以下操作：

.ts

.html

{{child.name}

感谢您的回答，我们不能在这里更改json，也不能在json中添加“checked:true”。不过，这是一种“正确”的方法。为什么不能添加选中的键？它们不必存在于“原始”json中，但您可能可以复制一份？检查修改后的演示您是否尝试过修改后的解决方案？

<li *ngFor="let child of nestedjson; let i = index"><input type="checkbox" checked>{{child.name}}</li>
<div><button (click)="clear()" type="submit">clear</button></div>

import { Component, OnInit } from '@angular/core';
import { FormBuilder, FormGroup, Validators } from '@angular/forms';
import Speech from 'speak-tts';
import { RxSpeechRecognitionService, resultList, } from '@kamiazya/ngx-speech-recognition';
@Component({
  selector: 'app-home',
  templateUrl: './home.component.html',
  styleUrls: ['./home.component.css'],

  providers: [ RxSpeechRecognitionService ]
})
export class HomeComponent implements OnInit {  
    showit:any;
    nestedjson:any;
 constructor(private formBuilder: FormBuilder,public service: RxSpeechRecognitionService) {
     }

  ngOnInit() {
       this.nestedjson = [
        { name: "parent1", value: ["child11", "child12"] },
        { name: "parent2", value: ["child2"] },
        { name: "parent3", value: ["child3"] }
      ];
      this.showit = true;

} 

clear(){

}

}

<li *ngFor="let child of nestedjson; let i = index">
  <input type="checkbox" [(ngModel)]="child.checked">
  {{child.name}}
</li>

<div><button (click)="clear()" type="submit">clear</button></div>

nestedjson = [
    { name: "parent1", value: ["child11", "child12"], checked: true },
    { name: "parent2", value: ["child2"], checked: true },
    { name: "parent3", value: ["child3"], checked: true }
  ];

  clear() {
    this.nestedjson.forEach(child => {
      child.checked = false
    })
  }

checkedItems = this.nestedjson.map(x => ({ name: x.name, checked: true }));

<li *ngFor="let child of nestedjson; let i = index">
  <input type="checkbox" [(ngModel)]="checkedItems[i].checked">
  {{child.name}}
</li>