如何在使用angular8的编辑项中发生更改时抛出验证消息

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

@Component({
  selector: 'app-your-component',
  templateUrl: './your-component.component.html',
  styleUrls: ['./your-component.component.css']
})
export class YourComponent {
  form: FormGroup;

  constructor() {
    this.form = new FormGroup({
      yourField: new FormControl('', Validators.required)
    });
  }

  onSubmit() {
    // 处理表单提交逻辑
  }
}

<form [formGroup]="form" (ngSubmit)="onSubmit()">
  <input type="text" formControlName="yourField" />
  <div *ngIf="form.controls.yourField.invalid && form.controls.yourField.touched">
    <div *ngIf="form.controls.yourField.errors.required">该字段为必填项。</div>
  </div>
  <button type="submit">提交</button>
</form>