java-tutorials/spring-security-modules/spring-security-web-angular/client/angular6/src/app/login/login.component.html

<form name="form" (ngSubmit)="f.form.valid && login()" #f="ngForm" novalidate>
    <div [ngClass]="{ 'has-error': f.submitted && !username.valid }">
        <label for="username">Username</label>
        <input type="text" name="username" [(ngModel)]="model.username" #username="ngModel" required />
        <div *ngIf="f.submitted && !username.valid">Username is required</div>
    </div>
    <div [ngClass]="{ 'has-error': f.submitted && !password.valid }">
        <label for="password">Password</label>
        <input type="password" name="password" [(ngModel)]="model.password" #password="ngModel" required />
        <div *ngIf="f.submitted && !password.valid">Password is required</div>
    </div>
    <div>
        <button [disabled]="loading">Login</button>
    </div>
</form>