title: Need assistance with Ionic 3 form group, cannot read property get of undefined
body: <p>I just made a register form, i used to use Form-Group in Angular 5, but with Ionic 3 i get the following errors:</p>
  
  <p>1- Cannot read property 'get' of undefined.</p>
  
  <p>2- ERROR Error: Uncaught (in promise): Error: formGroup expects a FormGroup 
  instance. Please pass one in.</p>
  
  <pre><code>   Example:
  
  
  &lt;div [formGroup]="myGroup"&gt;
    &lt;input formControlName="firstName"&gt;
  &lt;/div&gt;
  
  In your class:
  
  this.myGroup = new FormGroup({
     firstName: new FormControl()
  });
  </code></pre>
  
  <p>My HTML:</p>
  
  <pre><code>&lt;ion-list&gt;
    &lt;form [formGroup]="register" (ngSubmit)="createUser()"&gt;
    &lt;ion-item class="form-group" padding&gt;
      &lt;ion-label color="primary" floating&gt;Name&lt;/ion-label&gt;
      &lt;ion-input formControlName="name" class="form-control" type="text"&gt;
      &lt;/ion-input&gt;
    &lt;/ion-item&gt;
    &lt;ion-item class="form-group" padding&gt;
      &lt;ion-label color="primary" floating&gt;User Name&lt;/ion-label&gt;
      &lt;ion-input formControlName="userName" class="form-control" type="text"&gt; 
      &lt;/ion-input&gt;
     &lt;/ion-item&gt;
     &lt;ion-item class="form-group" padding&gt;
      &lt;ion-label color="primary" floating&gt;Email&lt;/ion-label&gt;
      &lt;ion-input formControlName="email" class="form-control" type="text"&gt; 
      &lt;/ion-input&gt;
     &lt;/ion-item&gt;
     &lt;ion-item padding class="form-group"&gt;
      &lt;ion-label color="primary" floating&gt;Password&lt;/ion-label&gt;
      &lt;ion-input formControlName="password" class="form-control" 
      type="password"&gt;&lt;/ion-input&gt;
      &lt;/ion-item&gt;
      &lt;button type="submit" [disabled]="!register.valid" ion-button 
      color="primary" clear icon-start&gt;
      &lt;ion-icon name="contact"&gt;&lt;/ion-icon&gt; Submit user&lt;/button&gt;
    &lt;/form&gt;
  &lt;/ion-list&gt;
  </code></pre>
  
  <p>My TS:</p>
  
  <pre><code>import { Validators, FormBuilder, FormGroup } from '@angular/forms';
  
  register: FormGroup;
  homePage = HelloIonicPage;
  constructor(public navCtrl: NavController, public navParams: NavParams, 
  private create: UsersData, private formBuilder: FormBuilder) {
  }
  ionViewDidLoad() {
  this.InitUserForm();
  console.log('ionViewDidLoad LoginPage');
  }
  InitUserForm() {
  let EMAIL_REGEXP = /^(([^&lt;&gt;()\[\]\\.,;:\s@"]+(\.[^&lt;&gt;()\[\]\\.,;:\s@"]+)*)| 
  (".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}])|(([a-zA-Z\-0- 
  9]+\.)+[a-zA-Z]{2,}))$/;
  this.register = this.formBuilder.group({
    id: [0],
    name: ['', [Validators.required]],
    userName: ['', [Validators.required]],
    email: ['', [Validators.required, Validators.pattern(EMAIL_REGEXP)]],
    password: ['', [Validators.required, Validators.minLength(6)]]
  })
  }
  createUser() {
  this.create.createUsers(this.register.value);
  }
  </code></pre>
  
  <p>What i have tried so far:</p>
  
  <p>1- Tried switching from ion-input to normal input tag.</p>
  
  <p>2- Tried adding FormsModule to app module.</p>
  
  <p>3- I double checked the documentation of Ionic Forms, and did everything they said.</p>
  
  <p>I need to know where is the issue, is it because i didn't add ngModel? i never use it when i use formGroup with Angular 5.</p>