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();
}