title: Update <ion-datetime> control data using formGroup
body: <p>I have a form that is built using 'FormBuilder' and it contains a date control . How can I set (update) data to that control using <code>patchValue()</code>?</p>
  
  <p>The control has <code>displayFormat="DD.MM.YYYY"</code> set in the template.</p>
  
  <p>Data on all other controls ( and ) is set , but the date control remains empty.</p>
  
  <p>page/component/.ts file</p>
  
  <pre><code>userDataForm: FormGroup;
  user: UserModel;
  
  constructor(
      private formBuilder: FormBuilder
  ) {
      this.userDataForm = this.buildForm();
  }
  
  buildForm(){
      return this.formBuilder.group({
          firstName: ['', Validators.compose([
            Validators.required
          ])],
          dateOfBirth: ['', Validators.compose([
            Validators.required
          ])]
      });
  }
  
  ionViewWillEnter() {
      // load data...
      refreshForm();
  }
  
  refreshForm(){
      this.userDataForm.patchValue({
          firstName: this.user.firstName,
          dateOfBirth: new Date("2016-04-19T18:03:40.887"), // does not work
      });
  }
  </code></pre>
  
  <p>Template:</p>
  
  <pre><code>&lt;ion-content padding&gt;
      &lt;ion-list&gt;
          &lt;form [formGroup]="userDataForm"&gt;
  
              &lt;ion-item&gt;
                  &lt;ion-label floating&gt;Name: *&lt;/ion-label&gt;
                  &lt;ion-input formControlName="firstName" type="text"&gt;&lt;/ion-input&gt;
              &lt;/ion-item&gt;
  
              &lt;ion-item&gt;
                  &lt;ion-label floating&gt;Date: *&lt;/ion-label&gt;
                  &lt;ion-datetime formControlName="dateOfBirth" displayFormat="DD.MM.YYYY"&gt;&lt;/ion-datetime&gt;
              &lt;/ion-item&gt;
  
          &lt;/form&gt;
      &lt;/ion-list&gt;
  &lt;/ion-content&gt;
  </code></pre>