Angular 2动态表单如何根据一个字段的值显示/隐藏另一个字段

<div>
  <label for="field1">字段1：</label>
  <input type="text" id="field1" [(ngModel)]="field1Value">
</div>

<div *ngIf="field1Value === 'show'">
  <label for="field2">字段2：</label>
  <input type="text" id="field2" [(ngModel)]="field2Value">
</div>

import { Component } from '@angular/core';

@Component({
  selector: 'app-form',
  templateUrl: './form.component.html',
  styleUrls: ['./form.component.css']
})
export class FormComponent {
  field1Value: string;
  field2Value: string;
}