ng_model_group.ts

@Directive({selector: '[ngModelGroup]', providers: [modelGroupProvider], exportAs: 'ngModelGroup'})
export class NgModelGroup extends AbstractFormGroupDirective implements OnInit, OnDestroy {
  @Input('ngModelGroup') name: string;

  constructor(
      @Host() @SkipSelf() parent: ControlContainer,
      @Optional() @Self() @Inject(NG_VALIDATORS) validators: any[],
      @Optional() @Self() @Inject(NG_ASYNC_VALIDATORS) asyncValidators: any[]) {
    super();
    this._parent = parent;
    this._validators = validators;
    this._asyncValidators = asyncValidators;
  }

  /** @internal */
  _checkParentType(): void {
    if (!(this._parent instanceof NgModelGroup) && !(this._parent instanceof NgForm)) {
      TemplateDrivenErrors.modelGroupParentException();
    }
  }
}