角度材料：尽管有正确的方法，但垫子错误并未显示

我有一个要验证的确认密码表单控件。

当密码与确认密码输入中的值不同时，我想显示我的 mat-error 元素。为此我有一个名为equalPasswords()。如果功能相同，则我们收到 true，如果不同，我们收到 false。

<mat-form-field>
              <input matInput placeholder="Repeat password" [formControl]="password2" type="password">
              <mat-error *ngIf="password2.invalid && password2.hasError('required')">Password is required</mat-error>
              <mat-error *ngIf="!equalPasswords() && !password2.hasError('required')">Passwords need to match</mat-error>
</mat-form-field>

我检查了控制台，当我在密码框中输入两个不同的输入时， equalPasswords() 返回 false。然而它仍然没有在 DOM 中显示错误。

有人知道如何解决这个问题吗？

Signup.component.ts

@Component({
    selector: 'app-sign-up',
    templateUrl: 'sign-up.component.html',
    styleUrls: ['sign-up.component.css']
})

export class SignUpComponent implements OnInit {

    mySignupForm: FormGroup;
    countries = countries;
    uniqueUsernameMessage;
    uniqueEmailMessage;
    formSubmitted = false;
    @Output() closeSubmenu = new EventEmitter();
    @ViewChild('select') select;

    constructor(
        private authService: AuthenticationService,
        private route: Router,
        private navigationService: NavigationService){}

    get firstName() { return this.mySignupForm.get('firstName'); }
    get lastName() { return this.mySignupForm.get('lastName'); }
    get username() { return this.mySignupForm.get('username'); }
    get email() { return this.mySignupForm.get('email'); }
    get password1() { return this.mySignupForm.get('password1'); }
    get password2() { return this.mySignupForm.get('password2'); }
    get birthDate() { return this.mySignupForm.get('birthDate'); }
    get country() { return this.mySignupForm.get('country'); }
    get house() { return this.mySignupForm.get('house'); }

    ngOnInit() {
        this.mySignupForm = new FormGroup({
            firstName: new FormControl(null, Validators.required),
            lastName: new FormControl(null, Validators.required),
            username: new FormControl(null, [Validators.required, Validators.minLength(5), Validators.maxLength(15)]),
            birthDate: new FormControl(null, Validators.required),
            password1: new FormControl(null, [Validators.required, Validators.minLength(6), Validators.maxLength(15), Validators.pattern('^.*(?=.{4,10})(?=.*\\d)(?=.*[a-zA-Z]).*$')]),
            password2: new FormControl(null, Validators.required),
            email: new FormControl(null, [Validators.required, Validators.email]),
            country: new FormControl(null, Validators.required),
            house: new FormControl(null, Validators.required)
        })
    }

    equalPasswords() {

        console.log('equaltest', this.password1.value === this.password2.value);
        return this.password1.value === this.password2.value;
    }

}

MatFormField只显示mat-error元素当FormControl有错误。它不会仅仅因为你告诉它通过而显示ngIfElse- 这只适用于表单控制状态。解决此问题的一种方法是创建自定义验证器并使用它来检查密码是否匹配。您还可以从您的字段中设置错误equalPasswords()功能。那应该是这样的：

equalPasswords(): boolean {

    const matched: boolean = this.password1.value === this.password2.value;

    console.log('equaltest', matched);

    if (matched) {
        this.signupForm.controls.password2.setErrors(null);
    } else {
        this.signupForm.controls.password2.setErrors({
           notMatched: true
        });
    }

    return matched;
}