相关疑难解决方法(0)

Given the example at https://material.angular.io/components/form-field/overview

<div class="example-container">
  <mat-form-field>
    <input matInput placeholder="Enter your email" [formControl]="email" required>
    <mat-error *ngIf="email.invalid">{{getErrorMessage()}}</mat-error>
  </mat-form-field>
</div>


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

/** @title Form field with error messages */
@Component({
  selector: 'form-field-error-example',
  templateUrl: 'form-field-error-example.html',
  styleUrls: ['form-field-error-example.css']
})
export class FormFieldErrorExample {
  email = new FormControl('', [Validators.required, Validators.email]);

  getErrorMessage() {
    return this.email.hasError('required') ? 'You must enter a value' :
        this.email.hasError('email') ? 'Not a valid email' :
            '';
  }
}

The error seems to be …