Dividing a form into multiple components with validation

There is a way to do that in template driven forms too. ngModel creates automatically a separate form on each component, but you can inject the form of the parent component by adding this to your component:

@Component({
viewProviders: [{ provide: ControlContainer, useExisting: NgForm}]
}) export class ChildComponent

You have to make sure though, that each input has a unique name. So if you use *ngFor to call your child component, you have to put the index (or any other unique identifier) into the name , e.g.:

[name]="'address_' + i"

If you want to structure your form into FormGroups, you use ngModelGroup and

viewProviders: [{ provide: ControlContainer, useExisting: NgModelGroup }]

instead of ngForm and add [ngModelGroup]="yourNameHere" to some of your child components html containing tags.

I would use a reactive form which works quite nicely, and as to your comment:

Is there any other simple example for this one? Maybe the same example without loops

I can give you an example. All you need to do, is to nest a FormGroup and pass that on to the child.

Let's say your form looks like this, and you want to pass address formgroup to child:

ngOnInit() {
  this.myForm = this.fb.group({
    name: [''],
    address: this.fb.group({ // create nested formgroup to pass to child
      street: [''],
      zip: ['']
    })
  })
}

Then in your parent, just pass the nested formgroup:

<address [address]="myForm.get('address')"></address>

In your child, use @Input for the nested formgroup:

@Input() address: FormGroup;

And in your template use [formGroup]:

<div [formGroup]="address">
  <input formControlName="street">
  <input formControlName="zip">
</div>

If you do not want to create an actual nested formgroup, you don't need to do that, you can just then pass the parent form to the child, so if your form looks like:

this.myForm = this.fb.group({
  name: [''],
  street: [''],
  zip: ['']
})

you can pass whatever controls you want. Using the same example as above, we would only like to show street and zip, the child component stays the same, but the child tag in template would then look like:

<address [address]="myForm"></address>

Here's a

Demo of first option, here's the second Demo

More info here about nested model-driven forms.