title: Angular 4 - resetting a Reactive Form
body: <p>Using Reactive Forms, I have created some controls</p>
  
  <pre><code> ngOnInit() {
      this.myForm = new FormGroup({
        'name': new FormControl(null),
        'city': new FormControl('London'),
        'structure': new FormGroup({
          'Parallel': new FormControl('Parallel'),
          'Hierarchical': new FormControl('Hierarchical'),
          'Stable': new FormControl('Stable'),
        })
      })
  }
  </code></pre>
  
  <p>'name' and 'city' are rendered as a text field (with city having a default value) and 'structure' is rendered as checkboxes (all of them checked).</p>
  
  <p>Now, I need to provide an option to reset the form to default values. So, on click of Reset button, I am executing the following code</p>
  
  <pre><code> onReset() {
     //Leaving out 'name', as it does not have a default value
      this.myForm.reset({
        'city': 'London',
        'structure': ?????, //What should I do here
      });     
  }
  </code></pre>
  
  <p>form.reset resets the form. However, I also need to restore the default values. Restoring the default value of 'city' is easy since it's just a form control. However, how do I reset the values for 3 checkboxes inside 'structure' (which is a FormGroup)?</p>