Reactive forms: mark dirty all controls in form group

Question

I have Angular 6 app with form. Here is an examle

export class ExampleComponent implements OnInit {
    form: FormGroup;

    constructor(private fb: FormBuilder) { }

    ngOnInit() {
        this.form = new FormGroup({
            first: new FormControl(),
            last: new FormControl()
        });

        this.markControlsAsDirty(this.form);
    }

    markControlsAsDirty(form: FormGroup) {
        this.form.get('first').markAsDirty();
        this.form.get('last').markAsDirty();
    }
}

I don't want to get a single control and mark every field. Can I mark all controls in form group as dirty?

UPDATE I've been added stackblitz example to show that two previous answers were wrong

Answer 1

If you have a complicated form structure, you can segregate the code to mark FormGroup, FormArray or FormControl as dirty. See the example here : Mark Form as dirty

markDirty() {
  this.markGroupDirty(this.form);
  console.log('FORM:', this.form);
}
markGroupDirty(formGroup: FormGroup) {
  Object.keys(formGroup.controls).forEach((key) => {
    switch (formGroup.get(key).constructor.name) {
      case 'FormGroup':
        this.markGroupDirty(formGroup.get(key) as FormGroup);
        break;
      case 'FormArray':
        this.markArrayDirty(formGroup.get(key) as FormArray);
        break;
      case 'FormControl':
        this.markControlDirty(formGroup.get(key) as FormControl);
        break;
    }
  });
}
markArrayDirty(formArray: FormArray) {
  formArray.controls.forEach((control) => {
    switch (control.constructor.name) {
      case 'FormGroup':
        this.markGroupDirty(control as FormGroup);
        break;
      case 'FormArray':
        this.markArrayDirty(control as FormArray);
        break;
      case 'FormControl':
        this.markControlDirty(control as FormControl);
        break;
    }
  });
}
markControlDirty(formControl: FormControl) {
  formControl.markAsDirty();
}