确保在angular中至少选中一个复选框

<form [formGroup]="myForm">
  <label>
    <input type="checkbox" formControlName="checkbox1"> Checkbox 1
  </label>
  <label>
    <input type="checkbox" formControlName="checkbox2"> Checkbox 2
  </label>
  <label>
    <input type="checkbox" formControlName="checkbox3"> Checkbox 3
  </label>
</form>

import { Component, OnInit } from '@angular/core';
import { FormBuilder, FormGroup, Validators } from '@angular/forms';

@Component({
  selector: 'app-my-component',
  templateUrl: './my-component.component.html',
  styleUrls: ['./my-component.component.css']
})
export class MyComponentComponent implements OnInit {
  myForm: FormGroup;

  constructor(private formBuilder: FormBuilder) { }

  ngOnInit() {
    this.myForm = this.formBuilder.group({
      checkbox1: [false],
      checkbox2: [false],
      checkbox3: [false]
    }, { validators: this.checkAtLeastOneCheckbox });
  }

  checkAtLeastOneCheckbox(formGroup: FormGroup) {
    const checkbox1 = formGroup.get('checkbox1');
    const checkbox2 = formGroup.get('checkbox2');
    const checkbox3 = formGroup.get('checkbox3');

    if (!(checkbox1.value || checkbox2.value || checkbox3.value)) {
      return { requireOneCheckboxToBeChecked: true };
    }

    return null;
  }
}

<form [formGroup]="myForm">
  <!-- 复选框代码省略 -->
  
  <div *ngIf="myForm.errors?.requireOneCheckboxToBeChecked">
    请至少选中一个复选框。
  </div>
</form>