use of permission_required decorators on django class-based views

You can add the decorator in urls.py, e.g.,
login_required(ViewSpaceIndex.as_view(..))

or

decorate the dispatch method with method_decorator e.g.,

from django.utils.decorators import method_decorator

@method_decorator(login_required)
def dispatch(self, *args, **kwargs):
    return super(ViewSpaceIndex, self).dispatch(*args, **kwargs)

or 

 @method_decorator(check_user_allowed(

allowed_user_types_list=[SUPER_ADMIN_KEY, ADMIN_KEY],

 need_org_check=True))
    def get(self, request, organization_id):
        form = MapLicensesForm(request.user, organization_id)
        params = {}
        params['form'] = form
        params['current_organization_id'] = organization_id
        #params['license_types'] = [val[0] for index, val in enumerate(filter(lambda x: x[0] != 'AppServer', get_license_type_choices()))]
        params['lic_types_obj'] = get_license_type_choices_obj()
        params['template_params'] = TemplateParams(organization_id)
        return render(request, 'iadmin/map_license.html', params)