What it does
Creates and binds a
FormGroup instance to a DOM element.
How to use
This directive can only be used as a child of
NgForm (or in other words,
Use this directive if you'd like to create a sub-group within a form. This can come in handy if you want to validate a sub-group of your form separately from the rest of your form, or if some values in your domain model make more sense to consume together in a nested object.
Pass in the name you'd like this sub-group to have and it will become the key
for the sub-group in the form's full value. You can also export the directive into
a local template variable using
exported from @angular/forms/index, defined in @angular/forms/src/directives/ng_model_group.ts