The ngModelGroup directive allows you to group together related inputs so that you structure the object represented by the form in a useful and predictable way. ngModelGroup is often used in combination with fieldset as they mostly represent the same idea of “grouping together inputs.”
<form name="myForm2" #formRef2="ngForm" (ngSubmit)="onSubmit(formRef2.value)">
<fieldset ngModelGroup="login">
<legend>Login:</legend> Username: <input type="text" name="username" ngModel required>
Password: <input type="password" name="password" ngModel requried> </fieldset>
</form>
<pre>
form value: {{formRef2.value | json}}
form valid: {{formRef2.valid | json}}
</pre>