login-form.component.html

<form (ngSubmit)="onSignInSubmit()" #f="ngForm" >


  <div class="row">

    <div class="input-field col s12">
      <input id="email"
             type="email"
             required
             name='email' 
             [(ngModel)]="signInUser.email" 
             class="validate">
      
      <label for="email">Email</label>
    </div>


    <div class="input-field col s12">
      <input id="password" 
             type="password" 
             required  
             name='password' 
             [(ngModel)]="signInUser.password" 
             class="validate">
      
      <label for="password">Password</label>
    </div>

    <div class="col s12 ">
      <button type="submit" 
              [disabled]="!(f.valid)" 
              [ngClass]="{'disabled': !(f.valid)}" 
              class="waves-effect waves-light btn blue right"
      > 
        Login </button>
    </div>


  </div>

</form>