如何在Ionic中有条件地要求表单输入？

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

@Component({
  selector: 'app-conditional-form',
  templateUrl: './conditional-form.page.html',
  styleUrls: ['./conditional-form.page.scss'],
})
export class ConditionalFormPage {
  form: FormGroup;

  constructor(private fb: FormBuilder) {
    this.form = this.fb.group({
      name: ['', Validators.required],
      email: ['', []],
      age: ['', []],
    });
  }

  toggleEmailRequirement() {
    if (this.form.get('name').value.length > 3) {
      this.form.get('email').setValidators([Validators.required]);
    } else {
      this.form.get('email').clearValidators();
    }
    this.form.get('email').updateValueAndValidity();
  }
}

<ion-header>
  <ion-toolbar>
    <ion-title>Conditional Form</ion-title>
  </ion-toolbar>
</ion-header>

<ion-content>
  <form [formGroup]="form">
    <ion-item>
      <ion-label>Name</ion-label>
      <ion-input formControlName="name" (ionChange)="toggleEmailRequirement()"></ion-input>
    </ion-item>
    <ion-item *ngIf="form.get('email').errors?.required">
      <ion-label>Email is required</ion-label>
    </ion-item>
    <ion-item>
      <ion-label>Email</ion-label>
      <ion-input formControlName="email"></ion-input>
    </ion-item>
    <ion-item>
      <ion-label>Age</ion-label>
      <ion-input formControlName="age"></ion-input>
    </ion-item>
    <ion-button type="submit" [disabled]="form.invalid">Submit</ion-button>
  </form>
</ion-content>