title: Form Validation after updating Ionic
body: <p>I had a Form Validation working but after updating Ionic doesn't work. Here's my code:</p>
  
  <p>form.html</p>
  
  <pre><code>&lt;ion-header&gt;
      &lt;ion-navbar&gt;
          &lt;ion-title&gt;
              Authorization Form Demo
          &lt;/ion-title&gt;
      &lt;/ion-navbar&gt;
  &lt;/ion-header&gt;
  
  &lt;ion-content class="home" padding&gt;
      &lt;form [ngFormModel]="authForm" (ngSubmit)="onSubmit(authForm.value)"&gt;
          &lt;ion-item [class.error]="!username.valid &amp;&amp; username.touched"&gt;
              &lt;ion-label floating&gt;Username&lt;/ion-label&gt;
              &lt;ion-input type="text" value="" [ngFormControl]="username"&gt;&lt;/ion-input&gt;         
          &lt;/ion-item&gt;
          &lt;div *ngIf="username.hasError('required') &amp;&amp; username.touched" 
              class="error-box"&gt;* Username is required!&lt;/div&gt;
          &lt;div *ngIf="username.hasError('minlength') &amp;&amp; username.touched" 
              class="error-box"&gt;* Minimum username length is 8!&lt;/div&gt;            
          &lt;div *ngIf="username.hasError('checkFirstCharacterValidator') &amp;&amp; username.touched" 
              class="error-box"&gt;* Username cant't start with number!&lt;/div&gt;                       
          &lt;ion-item [class.error]="!password.valid &amp;&amp; password.touched"&gt;
              &lt;ion-label floating&gt;Password&lt;/ion-label&gt;
              &lt;ion-input type="text" value="" [ngFormControl]="password" &gt;&lt;/ion-input&gt;
          &lt;/ion-item&gt;
          &lt;div *ngIf="password.hasError('required') &amp;&amp; password.touched" 
              class="error-box"&gt;* Password is required&lt;/div&gt;    
          &lt;div *ngIf="password.hasError('minlength') &amp;&amp; password.touched" 
              class="error-box"&gt;* Minimum password length is 8!&lt;/div&gt;                     
          &lt;div *ngIf="password.hasError('checkFirstCharacterValidator') &amp;&amp; password.touched" 
              class="error-box"&gt;* Password cant't start with number!&lt;/div&gt;             
          &lt;br/&gt;&lt;br/&gt; 
          &lt;button type="submit" class="custom-button" [disabled]="!authForm.valid" block&gt;Submit&lt;/button&gt;
      &lt;/form&gt;
  &lt;/ion-content&gt;
  </code></pre>
  
  <p>form.ts</p>
  
  <pre><code>import {Component} from '@angular/core';
  import {NavController} from 'ionic-angular';
  import {FORM_DIRECTIVES, FormBuilder,  ControlGroup, Validators, AbstractControl} from '@angular/common';
  import {CustomValidators} from '../validators/CustomValidators';
  
  
  @Component({
      templateUrl: 'build/pages/form/form.html',
      directives: [FORM_DIRECTIVES]
  })
  
  export class FormPage {
  
      authForm: ControlGroup;
      username: AbstractControl;
      password: AbstractControl;
  
      constructor(private navController: NavController, private fb: FormBuilder) {
          this.authForm = fb.group({  
              'username': ['', Validators.compose([Validators.required, Validators.minLength(8), CustomValidators.checkFirstCharacterValidator])],
              'password': ['', Validators.compose([Validators.required, Validators.minLength(8), CustomValidators.checkFirstCharacterValidator])]
          });
  
          this.username = this.authForm.controls['username'];     
          this.password = this.authForm.controls['password'];  
      }
  
      onSubmit(value: string): void { 
          if(this.authForm.valid) {
              console.log('Submitted value: ', value);
          }
      }   
  }
  </code></pre>
  
  <p>CustomValidators.ts</p>
  
  <pre><code>import { Control, ControlGroup } from "@angular/common";
  
  interface ValidationResult {
      [key: string]: boolean;
  }
  
  export class CustomValidators {
  
      public static checkFirstCharacterValidator(control: Control): ValidationResult {
          var valid = /^\d/.test(control.value);
          if (valid) {
              return {checkFirstCharacterValidator: true};
          }
          return null;
      }
  }
  </code></pre>
  
  <p>Somebody know what changes I need to do for working fine?
  Thanks in advance.</p>
  
  <p>Best regards.</p>